Monoclonal antibodies against antithrombin β

ABSTRACT

This patent document relates to antibodies, antigen-binding antibody fragments (Fabs), and other protein scaffolds, directed against human antithrombin β complexed with heparin and/or heparin-like structure (ATβH). These ATβH binding proteins can block the anti-coagulant activity of ATβ to induce coagulation. Therapeutic uses of these antibodies and binders are described herein as are methods of panning and screening specific antibodies.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is claims the benefit of U.S. provisional application No. 61/784,590, filed Mar. 14, 2013, the entire disclosure of which is hereby incorporated by reference in its entirety.

SEQUENCE LISTING SUBMISSION

The present application includes a Sequence Listing in electronic format as a txt file titled “Sequence_Listing_17207_0006USU2” which was created on Mar. 14, 2014 and which has a size of 65.1 kilobytes (KB). The contents of txt file “Sequence_Listing_17207_0006USU2” are incorporated by reference herein.

BACKGROUND

Current unmet medical needs in the hemophilia field are mainly: (1) treatment of hemophilia patients with inhibitors (˜30% of hemophilia patients); and (2) long acting and efficacious coagulant factors (FVIII/FIX) and/or their replacement (bypass drugs) (WFH report 2012, Paris). The most widely used bypass drug for treating hemophilia patients with inhibitors is rFVII, which has major drawbacks such as risk of thrombogenicity, short half-life in plasma and high production cost. Antibodies against anti-coagulant factors, such as Tissue Factor Protein Inhibitor (TFPI), APC (Activated Protein C) and Antithrombin (AT) represent a new treatment paradigm. These antibodies not only bypass or reduce the need for FVIII or FIX coagulation factors in hemophilia patients with inhibitors, but also exhibit longer plasma half-life (which reduces the dosing frequency) and, thus, increases patient compliance. To date, there have been several antibody-based procoagulant drugs at the preclinical development or research stage, such as anti-TFPI and anti-APC.

AT is a major anticoagulant in human plasma. It inhibits thrombin, FXa and other serine proteases functioning in the coagulation pathway. It consists of 432 amino acids, is produced by the liver hepatocyte and has a long plasma half-life of three days (Collen, Schetz et al. 1977). The amino acid sequence of AT is well-conserved and the homology among cow, sheep, rabbit, mouse and human is 84%-89% (Olson and Bjork 1994). Although the primary physiological targets of AT are thrombin and FXa, AT also inhibits FIXa, FXIa, FXIIa, as well as FVIIa to a lesser extent. AT exerts its inhibition together with heparin. In presence of heparin the inhibition rate of thrombin and FXa by AT increases by 3 to 4 orders of magnitude from 7-11×10³M⁻¹ s⁻¹ to 1.5-4×10⁷ M⁻¹ s⁻¹ and from 2.5×10⁻³ M⁻¹ s⁻¹ to 1.25-2.5 M⁻¹ s⁻¹ respectively (Olson, Swanson et al. 2004).

Unlike TFPI and APC which inhibit coagulation solely at the initiating stage and the amplification stage respectively, AT exerts its inhibition on coagulation at both the initiation and amplification stage. Therefore, blocking AT could have more potent pro-coagulant effect than blocking either TFPI or APC alone. Decreased AT levels and activity have been shown to correlate with increased thrombosis in human. Patients with AT deficiency tend to show recurrent venous thrombosis and pulmonary embolisms (van Boven and Lane 1997). Furthermore, homozygous AT knockout mice die in the embryonic stage with an extreme hypercoagulable state (Ishiguro, Kojima et al. 2000). A recent study shows that heterozygous AT knockout hema mice in which AT is reduced by 50% significantly have less blood loss and enhanced thrombin generation in a tail-clip bleeding model (Bolliger, Szlam et al. 2010).

AT is a glycoprotein with two isoforms based on differential glycosylation on Asn135, ATα and ATβ (Bjork 1997). ATβ lacks glycosylation at Asn135 and is a minor glyco-isoform representing 10% of human plasma AT. Asn135 is located adjacent to the initial heparin attachment site and constitutes part of extended heparin binding site after allosteric activation and D helix extension (dela Cruz, Jairajpuri et al. 2006). The lack of bulky-sized glycan at Asn135 affects ATβ activation profoundly in two ways: 1) a faster allosteric activation upon heparin binding required for inhibition of FXa and FIXa; and 2) extra accessible binding sites for higher affinity heparin binding for inhibition of FXa and thrombin by a bridging mechanism. Indeed, under physiological salt concentration, plasma-derived ATβ binds to heparin with a K_(D) of 36+/−3 nm while ATα binds to heparin with a K_(D) of 500+/−50 nm (Turk I V. et al., 1993). The higher affinity of ATβ for heparin leads to its preferential distribution to the sub-endothelial layer which is enriched in the heparin-like structure—glycosaminoglycan. Consequently, ATβ is proposed to play a major and potent role in inhibition of FXa and thrombin at the vascular injury sites (Carlson and Atencio 1982; McCoy A J, Pei X Y. et al. 2003; Turk B, Brieditis I. et al. 1997; Witmer M R, Hatton M W. 1991; Frebelius S, et al. 1996). The importance and stronger potency of ATβ relative to that of ATα is also reported in clinical studies. In patients, the severity of AT homozygous mutations defective in heparin-binding is ameliorated by the beta form of AT (Martinez-Martinez, Navarro-Fernandez et al. 2012). In another study, a borderline level (˜70% of normal AT antigen and activity) of AT is compensated by the 20%˜30% ATβ in plasma (Bayston, Tripodi et al. 1999).

SUMMARY

Monoclonal antibodies to human ATβH (ATβ complexed with heparin and/or heparin-like structure) are provided. In at least one embodiment, the anti-ATβH monoclonal antibodies exhibit binding to ATβ complexed with Heparin.

In other embodiments, the monoclonal antibodies to ATβH may be optimized, for example to have increased affinity or increased functional activity. Also provided are specific epitopes that may be on human ATβH and are bound by an isolated monoclonal antibody. Further provided are the isolated nucleic acid molecules encoding the same.

Pharmaceutical compositions comprising the anti-ATβH monoclonal antibodies and methods of treatment of genetic and acquired deficiencies or defects in coagulation such as hemophilia A and B are also provided.

Also provided are methods for shortening bleeding time by administering an anti-ATβH monoclonal antibody to a patient in need thereof. Methods for producing a monoclonal antibody that binds human ATβH are also provided.

BRIEF DESCRIPTION OF THE DRAWINGS

The skilled artisan will understand that the drawings, described below, are for illustration purposes only. The drawings are not intended to limit the scope of the present teachings or claims in any way.

FIG. 1 shows a schematic representation of ATβ bound to heparin and the various binding domains of ATβ.

FIGS. 2A-2C show how ATβ is distinguished from ATα by lacking of one N-glycan.

FIGS. 3A-3D show ATβ with faster binding to heparin and more potent inhibition than ATα.

FIG. 4A shows biotinlayted hAT and rAT are functional in inhibition of Fxa generation (FIG. 4A). FIGS. 4B-4C show various strategies for antibody discovery by phage display.

FIG. 5 shows a screening method for identifying antibodies capable of functional inhibition of ATβ::heparin.

FIGS. 6A and 6B shows alignment of the amino acid sequences of the light chain domain and heavy chain domain, respectively, of antibodies TPP-2009 (SEQ ID NO:1 and SEQ ID NO: 2, respectively), TPP-2015 (SEQ ID NO:3 and SEQ ID NO:4, respectively), TPP-2016 (SEQ ID NO:5 and SEQ ID NO:6 respectively), TPP-2019 (SEQ ID NO:7 and SEQ ID NO:8, respectively), and TPP-2803 (SEQ ID NO:9 and SEQ ID NO:10, respectively).

FIGS. 7A-7C show antibody binding specificity determined by Biacore (FIG. 7A) and ELISA (FIG. 7B) tests, and antibody binding affinity to human AtβH (FIG. 7C).

FIG. 8A is a graphical representation of the effect of TPP antibodies on thrombin generation in human HEM-A plasma, and illustrates that antibody presence increases peak thrombin generation in human HEM-A plasma.

FIG. 8B is a table showing antibodies shorten clotting time in human HemA plasma and in human AT-deficient plasma spiked in with Atβ or Atα.

FIG. 9 is a graphical representation of the PK of antibody TPP 2009 in HEM-A mice using IV dosing at 0.3, 3 and 30 mg/kg, three mice per time point (10 time points over 21 days), and associated PK parameters.

FIGS. 10A and 10B show an experimental protocol for a tail vein transection (TVT) model in HemA and the efficacy of antibody TPP-2009 in the TVT model in HemA mice. FIG. 10B shows the antibody TPP-2009 has potent efficacy in the Tail Vein Transection (TVT) model of HemA mice.

FIGS. 11A and 11B shows a molecular model of the three-dimensional structures of native ATβ complexed with/without heparin (FIG. 11A), and fully activated antibody TPP2009 bound to heparin (FIG. 11B) and its predicted epitope structure. Helix D is extended upon heparin binding B.

FIG. 12 shows a TPP2803 exhibited dose-dependent shortening of the clotting time in both normal human plasma and hemophilia patient plasma using the FXa activated clotting assay. CT: clotting time, HEM-A: Hemophilia A plasma.

FIG. 13 shows an experimental design of the heparinized rabbit bleeding model; Experimental groups: Vehicle, PBS; Positive control, Protamine sulfate, (28 mg/kg IV); Negative control, M14 IgG2; treatment: 30 mg/kg; TPP2803, 3 mg/kg; TPP2803, 30 mg/kg.

FIG. 14. shows the effect of a control and TPP2803 on bleeding time before and after LMWH and compound administration in a heparinized rabbit bleeding model.

FIG. 15. shows the effect of a control and TPP2803 on delta bleeding time Significantly different from PBS (p≦0.05; T-test).

FIG. 16. shows the effect of a control and TPP2803 on blood loss before and after LMWH and antibody administration. (Significance by the T-test).

DETAILED DESCRIPTION

This disclosure provides antibodies, including monoclonal antibodies and other binding proteins that specifically bind to the activated form of ATβ, but exhibit comparatively little or no reactivity against the ATα form, either naïve or activated.

DEFINITIONS

For the purpose of interpreting this specification, the following definitions will apply. In the event that any definition set forth below conflicts with the usage of that word in any other document, including any document incorporated herein by reference, the definition set forth below shall always control for purposes of interpreting this specification and its associated claims unless a contrary meaning is clearly intended (for example in the document where the term is originally used).

Whenever appropriate, terms used in the singular will also include the plural and vice versa. The use of “a” herein means “one or more” unless stated otherwise or where the use of “one or more” is clearly inappropriate. The use of “or” means “and/or” unless stated otherwise. The use of “comprise,” “comprises,” “comprising,” “include,” “includes,” and “including” are interchangeable and are not limiting. The terms “such as,” “for example,” and “e.g.” also are not intended to be limiting. For example, the term “including” shall mean “including, but not limited to.”

As used herein, the term “about” refers to +/−10% of the unit value provided. As used herein, the term “substantially” refers to the qualitative condition of exhibiting a total or approximate degree of a characteristic or property of interest. One of ordinary skill in the biological arts will understand that biological and chemical phenomena rarely, if ever, achieve or avoid an absolute result because of the many variables that affect testing, production, and storage of biological and chemical compositions and materials, and because of the inherent error in the instruments and equipment used in the testing, production, and storage of biological and chemical compositions and materials. The term substantially is therefore used herein to capture the potential lack of completeness inherent in many biological and chemical phenomena.

The term “ATβ” or “ATβH” as used herein refers to any variant, isoform, and/or species homolog of AT in its form that is naturally expressed by cells and present in plasma and is distinct from ATα. Further, the term “ATβ” or “ATβH” as used herein can also refer to an activated form of ATβ complexed with heparin or a heparin-like structure.

The term “antibody” as used herein refers to a whole antibody and any antigen binding fragment (i.e., “antigen-binding portion”) or single chain thereof. This term includes a full-length immunoglobulin molecule (e.g., an IgG antibody) that is naturally occurring or formed by normal immunoglobulin gene fragment recombinatorial processes, or an immunologically active portion of an immunoglobulin molecule, such as an antibody fragment, that retains the specific binding activity. Regardless of structure, an antibody fragment binds with the same antigen that is recognized by the full-length antibody. For example, an anti-ATβH monoclonal antibody fragment binds to an epitope of ATβH. The antigen-binding function of an antibody can be performed by fragments of a full-length antibody. Examples of binding fragments encompassed within the term “antigen-binding portion” of an antibody include: (i) a Fab fragment, a monovalent fragment consisting of the VL, VH, CL and CH1 domains; (ii) a F(ab′)2 fragment, a bivalent fragment comprising two Fab fragments linked by a disulfide bridge at the hinge region; (iii) a Fd fragment consisting of the VH and CH1 domains; (iv) a Fv fragment consisting of the VLand VH domains of a single arm of an antibody; (v) a dAb fragment (Ward et al., (1989) Nature 341:544-546), which consists of a V_(H) domain; (vi) an isolated complementarity determining region (CDR); (vii) minibodies, diabodies, triabodies, tetrabodies, and kappa bodies (see, e.g., Ill et al., Protein Eng 1997; 10:949-57); (viii) camel IgG; and (ix) IgNAR. Furthermore, although the two domains of the Fv fragment, V_(L) and V_(H), are coded for by separate genes, they can be joined, using recombinant methods, by a synthetic linker that enables them to be made as a single protein chain in which the V_(L) and V_(H) regions pair to form monovalent molecules (known as single chain Fv (scFv); see e.g., Bird et al. (1988) Science 242:423-426; and Huston et al (1988) Proc. Natl. Acad. Sci. USA 85:5879-5883). Such single chain antibodies are also encompassed within the term “antigen-binding portion” of an antibody. These antibody fragments are obtained using conventional techniques known to those with skill in the art, and the fragments are analyzed for utility in the same manner as are intact antibodies.

Furthermore, it is contemplated that an antigen binding fragment can be encompassed in an antibody mimetic. The term “antibody mimetic” or “mimetic” as used herein refers to a protein that exhibits binding activity similar to a particular antibody but is a smaller alternative antibody or a non-antibody protein. Such antibody mimetic can be comprised in a scaffold. The term “scaffold” refers to a polypeptide platform for the engineering of new products with tailored functions and characteristics.

The term “anti-ATβ antibody” as used herein refers to an antibody that specifically binds to an epitope of ATβ associated with heparin or heparin-like. When bound in vivo to an epitope of ATβH, the anti-ATβ antibodies disclosed herein augment one or more aspects of the blood clotting cascade.

The terms “inhibits binding” and “blocks binding” (e.g., referring to inhibition/blocking of binding of ATβ substrate to ATβH) as used herein are used interchangeably and encompass both partial and complete inhibition or blocking of a protein with its substrate, such as an inhibition or blocking by at least about 10%, about 20%, about 30%, about 40%, about 50%, about 60%, about 70%, about 80%, about 90%, about 95%, about 96%, about 97%, about 98%, about 99%, or about 100%.

In reference to the inhibition and/or blocking of binding of ATβ substrate to ATβ, the terms inhibition and blocking also include any measurable decrease in the binding affinity of ATβ and/or ATβH to a physiological substrate when in contact with an anti-ATβantibody as compared to ATβ not in contact with an anti-ATβ antibody, e.g., the blocking of the interaction of ATβ with its substrates by at least about 10%, about 20%, about 30%, about 40%, about 50%, about 60%, about 70%, about 80%, about 90%, about 95%, about 96%, about 97%, about 98%, about 99%, or about 100%.

The terms “monoclonal antibody” or “monoclonal antibody composition” as used herein refer to antibody molecules of single molecular composition. A monoclonal antibody composition displays a single binding specificity and affinity for a particular epitope. Accordingly, the term “human monoclonal antibody” as used herein refers to antibodies displaying a single binding specificity that have variable and constant regions derived from human germline immunoglobulin sequences. The human antibodies can include amino acid residues not encoded by human germline immunoglobulin sequences (e.g., mutations introduced by random or site-specific mutagenesis in vitro or by somatic mutation in vivo).

The term “isolated antibody” as used herein is intended to refer to an antibody which is substantially free of other biological molecules, including antibodies having different antigenic specificities (e.g., an isolated antibody that binds to ATβH is substantially free of antibodies that bind antigens other than ATβH). In some embodiments, the isolated antibody is at least about 75%, about 80%, about 90%, about 95%, about 97%, about 99%, about 99.9% or about 100% pure by dry weight. In some embodiments, purity can be measured by a method such as column chromatography, polyacrylamide gel electrophoresis, or HPLC analysis. An isolated antibody that binds to an epitope, isoform or variant of human ATβH can, however, have cross-reactivity to other related antigens, e.g., from other species (e.g., ATβH species homologs). Moreover, an isolated antibody can be substantially free of other cellular material and/or chemicals.

The term “specific binding” as used herein refers to antibody binding to a predetermined antigen. An antibody that exhibits specific binding typically binds to an antigen with an affinity of at least about 10⁵M⁻¹ and binds to that antigen with an affinity that is higher, for example at least two-fold greater, than its binding affinity for an irrelevant antigen (e.g., BSA, casein). The phrases “an antibody recognizing an antigen” and “an antibody specific for an antigen” are used interchangeably herein with the term “an antibody which binds specifically to an antigen.” As used herein, the term “minimal binding” refers to an antibody that does not bind to and/or exhibits low affinity to a specified antigen. Typically, an antibody having minimal binding to an antigen binds to that antigen with an affinity that is lower than about 10² M⁻¹ and does not bind to a predetermined antigen with higher affinity than it binds to an irrelevant antigen.

When used herein for an antibody such as an IgG antibody, the term “high affinity” refers to a binding affinity of at least about 10⁷ M⁻¹, in at least one embodiment at least about 10⁸ M⁻¹, in some embodiments at least about 10⁹ M⁻¹, about 10¹⁰ M⁻¹, about 10¹¹ M⁻¹ or greater, e.g., up to about 10¹³ M⁻¹ or greater. However, “high affinity” binding can vary for other antibody isotypes. For example, “high affinity” binding for an IgM isotype refers to a binding affinity of at least about 10⁷ M⁻¹.

The term “isotype” as used herein refers to the antibody class (e.g., IgM or IgG1) that is encoded by heavy chain constant region genes.

The terms “Complementarity-determining region” or “CDR” as used herein refers to one of three hypervariable regions within the variable region of the heavy chain or the variable region of the light chain of an antibody molecule that form the N-terminal antigen-binding surface that is complementary to the three-dimensional structure of the bound antigen. Proceeding from the N-terminus of a heavy or light chain, these complementarity-determining regions are denoted as “CDR1,” “CDR2,” and “CDR3,” respectively [Wu T T, Kabat E A, Bilofsky H, Proc Natl Acad Sci USA. 1975 December; 72(12):5107 and Wu T T, Kabat E A, J Exp Med. 1970 Aug. 1; 132(2):211]. CDRs are involved in antigen-antibody binding, and the CDR3 comprises a unique region specific for antigen-antibody binding. An antigen-binding site, therefore, can include six CDRs, comprising the CDR regions from each of a heavy and a light chain V region. The term “epitope” refers to the area or region of an antigen to which an antibody specifically binds or interacts, which in some embodiments indicates where the antigen is in physical contact with the antibody. Conversely, the term “paratope” refers to the area or region of the antibody on which the antigen specifically binds. Epitopes characterized by competition binding are said to be overlapping if the binding of the corresponding antibodies are mutually exclusive, i.e. binding of one antibody excludes simultaneous binding of another antibody. The epitopes are said to be separate (unique) if the antigen is able to accommodate binding of both corresponding antibodies simultaneously.

The term “competing antibodies” as used herein refers to antibodies that bind to about the same, substantially the same, essentially the same, or even the same epitope as an antibody against ATβH as described herein. Competing antibodies include antibodies with overlapping epitope specificities. Competing antibodies are thus able to effectively compete with an antibody as described herein for binding to ATβH. In some embodiments, the competing antibody can bind to the same epitope as the antibody described herein. Alternatively viewed, the competing antibody has the same epitope specificity as the antibody described herein.

The term “conservative substitutions” as used herein refers to modifications of a polypeptide that involve the substitution of one or more amino acids for amino acids having similar biochemical properties that do not result in loss of a biological or biochemical function of the polypeptide. A conservative amino acid substitution is one in which the amino acid residue is replaced with an amino acid residue having a similar side chain. Families of amino acid residues having similar side chains have been defined in the art. These families include amino acids with basic side chains (e.g., lysine, arginine, histidine), acidic side chains (e.g., aspartic acid, glutamic acid), uncharged polar side chains (e.g., glycine, asparagine, glutamine, serine, threonine, tyrosine, cysteine), nonpolar side chains (e.g., alanine, valine, leucine, isoleucine, proline, phenylalanine, methionine, tryptophan), beta-branched side chains (e.g., threonine, valine, isoleucine), and aromatic side chains (e.g., tyrosine, phenylalanine, tryptophan, histidine). Antibodies of the present disclosure can have one or more conservative amino acid substitutions yet retain antigen binding activity.

For nucleic acids and polypeptides, the term “substantial homology” as used herein indicates that two nucleic acids or two polypeptides, or designated sequences thereof, when optimally aligned and compared, are identical, with appropriate nucleotide or amino acid insertions or deletions, in at least about 80% of the nucleotides or amino 30 acids, usually at least about 85%, in some embodiments about 90%, about 91%, about 92%, about 93%, about 94%, or about 95%, in at least one embodiment at least about 96%, about 97%, about 98%, about 99%, about 99.1%, about 99.2%, about 99.3%, about 99.4%, or about 99.5% of the nucleotides or amino acids. Alternatively, substantial homology for nucleic acids exists when the segments will hybridize under selective hybridization conditions to the complement of the strand. Also included are nucleic acid sequences and polypeptide sequences having substantial homology to the specific nucleic acid sequences and amino acid sequences recited herein. The percent identity between two sequences is a function of the number of identical positions shared by the sequences (i.e., % homology=# of identical positions/total # of positions ×100), taking into account the number of gaps, and the length of each gap, that need to be introduced for optimal alignment of the two sequences. The comparison of sequences and determination of percent identity between two sequences can be accomplished using a mathematical algorithm, such as without limitation the ALIGNX™ in silico cloning and assembly module of the VECTORNTI™ sequence analysis application (Invitrogen Corp., Carlsbad, Calif.). For ALIGN™, the default parameters of multiple alignment are: gap opening penalty: 10; gap extension penalty: 0.05; gap separation penalty range: 8; % identity for alignment delay: 40.

The percent identity between two sequences is a function of the number of identical positions shared by the sequences (i.e., % homology=# of identical positions/total # of positions ×100), taking into account the number of gaps, and the length of each gap, which need to be introduced for optimal alignment of the two sequences. The comparison of sequences and determination of percent identity between two sequences can be accomplished using a mathematical algorithm, such as without limitation the ALIGNX™ in silico cloning and assembly module of the VECTORNTI™ sequence analysis application (Invitrogen Corp., Carlsbad, Calif.). For ALIGNX™, the default parameters of multiple alignment are: gap opening penalty: 10; gap extension penalty: 0.05; gap separation penalty range: 8; % identity for alignment delay: 40.

Another method for determining the an overall match between a query sequence (a sequence of the present disclosure) and a subject sequence, also referred to as a global sequence alignment, can be determined using the CLUSTALW computer program (Thompson et al., Nucleic Acids Research, 1994, 2(22): 4673-4680), which is based on the algorithm of Higgins et al., Computer Applications in the Biosciences (CABIOS), 1992, 8(2): 189-191. In a sequence alignment the query and subject sequences are both DNA sequences. The result of said global sequence alignment is in percent identity. Parameters that can be used in a CLUSTALW alignment of DNA sequences to calculate percent identity via pairwise alignments are: Matrix=IUB, k-tuple=1, Number of Top Diagonals=5, Gap Penalty=3, Gap Open Penalty=10, Gap Extension Penalty=0.1. For multiple alignments, the following CLUSTALW parameters can be used: Gap Opening Penalty=10, Gap Extension Parameter=0.05; Gap Separation Penalty Range=8; % Identity for Alignment Delay=40.

The nucleic acids can be present in whole cells, in a cell lysate, or in a partially purified or substantially pure form. A nucleic acid is “isolated” or “rendered substantially pure” when purified away from other cellular components with which it is normally associated in the natural environment. To isolate a nucleic acid, standard techniques such as the following can be used: alkaline/SDS treatment, CsCl banding, column chromatography, agarose gel electrophoresis and others well known in the art.

Monoclonal Antibodies Against ATβH

Bleeding disorders where homeostasis is deregulated in hemophilia or in trauma patients where the wound results in a temporary loss of hemostasis, can be treated by AT inhibitors. Antibodies, antigen-binding fragments thereof, and other AT-specific protein scaffolds can be used to provide targeting specificity to inhibit a subset of AT protein functions while preserving the rest. Given the at least 10-fold difference in plasma concentration of ATβ (<12 ug/ml) versus ATα (120 ug/ml), increased specificity of any potential ATβ inhibitor therapeutics is helpful to block ATβ function in the presence of a high circulating excess of ATα. ATβ specific antibodies that block the anti-coagulant function of ATβ can be used as therapeutics for patients with bleeding disorders. Examples of bleeding disorders include hemophilia, hemophilia patients with inhibitors, trauma-induced coagulopathy, severe bleeding patients during sepsis treatment by AT, bleeding resulting from elective surgery such as transplantation, cardiac surgery, orthopedic surgery, and excessive bleeding from Menorrhagia. Anti-ATβH antibodies having long circulating half-live can be useful in treating chronic diseases like hemophilia. ATβH antibody fragments or ATβH-binding protein scaffolds with shorter half-lives can be more effective for acute use (e.g. therapeutic use in trauma). ATβH-binding antibodies were identified by panning and screening human antibody libraries against human ATβ in complex with heparin. The identified antibodies exhibited binding to human ATβH. The heavy chain variable region and light chain variable region of each monoclonal antibody isolated was sequenced and its CDR regions were identified. The sequence identifier numbers (“SEQ ID NO”) that correspond to the heavy and light chain variable regions of the ATβH-specific monoclonal antibodies are summarized in Table 1A.

TABLE 1A Human anti-ATβH (heparin complexed ATβ) antibodies Clone Light Chain variable Region SEQ ID Heavy Chain Variable Region SEQ ID TPP2009 AQSVLTQDPAVSVALGQTVRITCQGDS No. 1 EVQLLESGGGLVQPGGSLRLSCAASGF No. 2 LRSYYASWYQQKPGQAPVLVIYGKNNR TFSAYRMGWVRQAPGKGLEWVSRIYSS PSGIPDRFSGSSSGNTASLTITGAQAE GGRTRYADSVKGRFTISRDNSKNTLYL DEADYYCNSRDSSGNHLVFGGGTKLTV QMNSLRAEDTAVYYCAREKASDLSGSF LGQPKAAPSVTLFPPSSEELQANKATL SEALDYWGQGTLVTVSS VCLISDFYPGAVTVAWKADGSPVKAGV ETTKPSKQSNNKYAASSYLSLTPEQWK SHRSYSCQVTHEGSTVEKTVAPAECS TPP2015 AQDIQMTQSPGTLSLSPGERATLSCRA No. 3 EVQLLESGGGLVQPGGSLRLSCAASGF No. 4 SQSVSSSYLAWYQQKPGQAPRLLIYGA TFSKYKMDWVRQAPGKGLEWVSRIGPS SSRATGIPDRFSGSGSGTDFTLTISRL GGKTMYADSVKGRFTISRDNSKNTLYL EPEDFAVYYCQQYGSSRTFGQGTKVEI QMNSLRAEDTAVYYCAREKASDLSGTY RRTVAAPSVFIFPPSDEQLKSGTASVV SEALDYWGQGTLVTVSS CLLNNFYPREAKVQWKVDNALQSGNSQ ESVTEQDSKDSTYSLSSTLTLSKADYE KHKVYACEVTHQGLSSPVTKSFNRG EC TPP2016 AQDIQMTQSPATLSVSPGERATLSCRA No. 5 EVQLLESGGGLVQPGGSLRLSCAASGF No. 6 SQNINRNLAWYQQKPGRAPRLLIHTAS TFSKYRMDWVRQAPGKGLEWVSRIGPS TRAPGVPVRITGSGSGTEFTLTISSLE GGKTTYADSVKGRFTISRDNSKNTLYL PEDFAVYFCQQYASPPRTFGQGTKVEI QMNSLRAEDTAVYYCAREKTSDLSGSY KRTVAAPSVFIFPPSDEQLKSGTASVV SEALDYWGQGTLVTVSS CLLNNFYPREAKVQWKVDNALQSGNSQ ESVTEQDSKDSTYSLSSTLTLSKADY EKHKVYACEVTHQGLSSPVTKSFNRG EC TPP2019 AQDIQMTQSPATLSLSPGERATLSCRA No. 7 EVQLLESGGGLVQPGGSLRLSCAASGF No. 8 SQRVSSSYLTWYQQKPGQAPRLLIYGA TFSRYAMYWVRQAPGKGLEWVSRISPS SSRATGIPDRFSGSGSGTDFTLTISRL GGKTHYADSVKGRFTISRDNSKNTLYL EPEDFAVYYCQQYDSTPPLTFGGGTKV QMNSLRAEDTAVYYCARLSQTGYYPHY EIKRTVAAPSVFIFPPSDEQLKSGTAS HYYGMDVWGQGTTVTVSS VVCLLNNFYPREAKVQWKVDNALQSGN SQESVTEQDSKDSTYSLS STLTLSKADYEKHKVYACEVTHQGLSS PVTKSFNRGEC TPP2803 SSELTQDPAVSVALGQTVRITCQGDSL No. 9 EVQLLESGGGLVQPGGSLRLSCAASGF No. 10 RSYYASWYQQKPGQAPVLVIYGKNNRP TFSSYRMSWVRQAPGKGLEWVSRIYSS SGIPDRFSGSSSGNTASLTITGAQAED GGRTRYADSVKGRFTISRDNSKNTLYL EADYYCNSRDSSGNHLVFGGGTKLTVL QMNSLRAEDTAVYYCAREKASDLSGSF GQPKAAPSVTLFPPSSEELQANKATLV SEALDYWGQGTLVTVSS CLISDFYPGAVTVAWKADGSPVKAGVE TTKPSKQSNNKYAASSYLSLTPEQWKS HRSYSCQVTHEGSTVEKTVAPAECS

In at least some possible embodiments, an isolated monoclonal antibody binds to human ATβH and inhibits anticoagulant activity, wherein the antibody comprises a heavy chain variable region comprising an amino acid sequence selected from the group consisting of SEQ ID NOS: 2, 4, 6, 8, and 10.

In at least some possible embodiments, an isolated monoclonal antibody binds to human ATβH and inhibits anticoagulant activity, wherein the antibody comprises a light chain variable region comprising an amino acid sequence selected from the group consisting of SEQ ID NOS: 1, 3, 5, 7, and 9.

In at least some possible embodiments an isolated monoclonal antibody binds to human ATβH and inhibits anticoagulant activity, wherein the antibody comprises a heavy chain variable region comprising an amino acid sequence selected from the group consisting of SEQ ID NOS: 2, 4, 6, 8, and 10 and a light chain variable region comprising an amino acid sequence selected from the group consisting of SEQ ID NOS: 1, 3, 5, 7, and 9.

In at least some possible embodiments, the antibody comprises heavy and light chain variable regions comprising:

-   -   (a) a heavy chain variable region comprising an amino acid         sequence of SEQ ID NO: 2, and a light chain variable region         comprising an amino acid sequence of SEQ ID NO: 1;     -   (b) a heavy chain variable region comprising an amino acid         sequence of SEQ ID NO: 4, and a light chain variable region         comprising an amino acid sequence of SEQ ID NO: 3;     -   (c) a heavy chain variable region comprising an amino acid         sequence of SEQ ID NO: 6, and a light chain variable region         comprising an amino acid sequence of SEQ ID NO: 5; or     -   (d) a heavy chain variable region comprising an amino acid         sequence of SEQ ID NO: 8, and a light chain variable region         comprising an amino acid sequence of SEQ ID NO: 7; or     -   (e) a heavy chain variable region comprising an amino acid         sequence of SEQ ID NO: 10, and a light chain variable region         comprising an amino acid sequence of SEQ ID NO: 9.

Table 1B shows heavy and light chain amino acid sequences for humanized IgG mAbs.

TABLE 1B Heavy and Light Chain Amino Acid Sequences  for humanized IgG mAbs. TPP2009|hIgG1|Light_Chain SEQ ID NO: 51 AQSVLTQDPAVSVALGQTVRITCQGDSLRSYYASWYQQKPGQAPVLVIYG KNNRPSGIPDRFSGSSSGNTASLTITGAQAEDEADYYCNSRDSSGNHLVF GGGTKLTVLGQPKAAPSVTLFPPSSEELQANKATLVCLISDFYPGAVTVA WKADGSPVKAGVETTKPSKQSNNKYAASSYLSLTPEQWKSHRSYSCQVTH EGSTVEKTVAPAECS TPP2009|hIgG|Heavy_chain SEQ ID NO: 52 EVQLLESGGGLVQPGGSLRLSCAASGFTFSAYRMGWVRQAPGKGLEWVSR IYSSGGRTRYADSVKGRFTISRDNSKNTLYLQMNSLRAEDTAVYYCAREK ASDLSGSFSEALDYWGQGTLVTVSSASTKGPSVFPLAPSSKSTSGGTAAL GCLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSSGLYSLSSVVTVPSSS LGTQTYICNVNHKPSNTKVDKKVEPKSCDKTHTCPPCPAPELLGGPSVFL FPPKPKDTLMISRTPEVTCVVVDVSHEDPEVKFNWYVDGVEVHNAKTKPR EEQYNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKALPAPIEKTISKAKGQ PREPQVYTLPPSRDELTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYK TTPPVLDSDGSFFLYSKLTVDKSRWQQGNVFSCSVMHEALHNHYTQKSLS LSPG  TPP-2015|hIgG|light_chain SEQ ID NO: 53 AQDIQMTQSPGTLSLSPGERATLSCRASQSVSSSYLAWYQQKPGQAPRLL IYGASSRATGIPDRFSGSGSGTDFTLTISRLEPEDFAVYYCQQYGSSRTF GQGTKVEIRRTVAAPSVFIFPPSDEQLKSGTASVVCLLNNFYPREAKVQW KVDNALQSGNSQESVTEQDSKDSTYSLSSTLTLSKADYEKHKVYACEVTH  QGLSSPVTKSFNRGEC TPP-2015|hIgG|heavy_chain SEQ ID NO: 54 EVQLLESGGGLVQPGGSLRLSCAASGFTFSKYKMDWVRQAPGKGLEWVSR IGPSGGKTMYADSVKGRFTISRDNSKNTLYLQMNSLRAEDTAVYYCAREK ASDLSGTYSEALDYWGQGTLVTVSSASTKGPSVFPLAPSSKSTSGGTAAL GCLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSSGLYSLSSVVTVPSSS LGTQTYICNVNHKPSNTKVDKKVEPKSCDKTHTCPPCPAPELLGGPSVFL FPPKPKDTLMISRTPEVTCVVVDVSHEDPEVKFNWYVDGVEVHNAKTKPR EEQYNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKALPAPIEKTISKAKGQ PREPQVYTLPPSRDELTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYK TTPPVLDSDGSFFLYSKLTVDKSRWQQGNVFSCSVMHEALHNHYTQKSLS LSG  TPP-2016|hIgG|light_chain, Kappa SEQ ID NO: 55 AQDIQMTQSPATLSVSPGERATLSCRASQNINRNLAWYQQKPGRAPRLLI HTASTRAPGVPVRITGSGSGTEFTLTISSLEPEDFAVYFCQQYASPPRTF GQGTKVEIKRTVAAPSVFIFPPSDEQLKSGTASVVCLLNNFYPREAKVQW KVDNALQSGNSQESVTEQDSKDSTYSLSSTLTLSKADYEKHKVYACEVTH  QGLSSPVTKSFNRGEC TPP-2016|hIgG|heavy_chain SEQ ID NO: 56 EVQLLESGGGLVQPGGSLRLSCAASGFTFSKYRMDWVRQAPGKGLEWVSR IGPSGGKTTYADSVKGRFTISRDNSKNTLYLQMNSLRAEDTAVYYCAREK TSDLSGSYSEALDYWGQGTLVTVSSASTKGPSVFPLAPSSKSTSGGTAAL GCLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSSGLYSLSSVVTVPSSS LGTQTYICNVNHKPSNTKVDKKVEPKSCDKTHTCPPCPAPELLGGPSVFL FPPKPKDTLMISRTPEVTCVVVDVSHEDPEVKFNWYVDGVEVHNAKTKPR EEQYNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKALPAPIEKTISKAKGQ PREPQVYTLPPSRDELTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYK TTPPVLDSDGSFFLYSKLTVDKSRWQQGNVFSCSVMHEALHNHYTQKSLS LSPG TPP-2019|hIgG|light_chain, Kappa SEQ ID NO: 57 AQDIQMTQSPATLSLSPGERATLSCRASQRVSSSYLTWYQQKPGQAPRLL IYGASSRATGIPDRFSGSGSGTDFTLTISRLEPEDFAVYYCQQYDSTPPL TFGGGTKVEIKRTVAAPSVFIFPPSDEQLKSGTASVVCLLNNFYPREAKV QWKVDNALQSGNSQESVTEQDSKDSTYSLSSTLTLSKADYEKHKVYACEV THQGLSSPVTKSFNRGEC TPP-2019|hIgG|heavy_chain SEQ ID NO: 58 EVQLLESGGGLVQPGGSLRLSCAASGFTFSRYAMYWVRQAPGKGLEWVSR ISPSGGKTHYADSVKGRFTISRDNSKNTLYLQMNSLRAEDTAVYYCARLS QTGYYPHYHYYGMDVWGQGTTVTVSSASTKGPSVFPLAPSSKSTSGGTAA LGCLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSSGLYSLSSVVTVPSS SLGTQTYICNVNHKPSNTKVDKKVEPKSCDKTHTCPPCPAPELLGGPSVF LFPPKPKDTLMISRTPEVTCVVVDVSHEDPEVKFNWYVDGVEVHNAKTKP REEQYNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKALPAPIEKTISKAKG QPREPQVYTLPPSRDELTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNY KTTPPVLDSDGSFFLYSKLTVDKSRWQQGNVFSCSVMHEALHNHYTQKSL SLSPG 

Table 1C—shows TPP2803 IgG2, Germlined and converted to IgG2. TPP2803 IgG2 light chain G2, Lambda, amino acid sequence shown in Table 1C is SEQ ID NO:59 and TPP2803 heavy chain amino acid sequence shown in Table 1C is SEQ ID NO: 60.

TABLE 1C TPP2803 IgG2, Germlined and converted to IgG2 >TPP-2803|hIgG2|light_chain, lambda SEQ ID NO: 59 SSELTQDPAVSVALGQTVRITCQGDSLRSYYASWYQQKPGQAPVLVIYGK NNRPSGIPDRFSGSSSGNTASLTITGAQAEDEADYYCNSRDSSGNHLVFG GGTKLTVLGQPKAAPSVTLFPPSSEELQANKATLVCLISDFYPGAVTVAW KADGSPVKAGVETTKPSKQSNNKYAASSYLSLTPEQWKSHRSYSCQVTHE GSTVEKTVAPAECS >TPP-2803|hIgG2|heavy_chain SEQ ID NO: 60 EVQLLESGGGLVQPGGSLRLSCAASGFTFSSYRMSWVRQAPGKGLEWVSR IYSSGGRTRYADSVKGRFTISRDNSKNTLYLQMNSLRAEDTAVYYCAREK ASDLSGSFSEALDYWGQGTLVTVSSASTKGPSVFPLAPCSRSTSESTAAL GCLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSSGLYSLSSVVTVPSSN FGTQTYTCNVDHKPSNTKVDKTVERKCCVECPPCPAPPVAGPSVFLFPPK PKDTLMISRTPEVTCVVVDVSHEDPEVQFNWYVDGVEVHNAKTKPREEQF NSTFRVVSVLTVVHQDWLNGKEYKCKVSNKGLPAPIEKTISKTKGQPREP QVYTLPPSREEMTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPP MLDSDGSFFLYSKLTVDKSRWQQGNVFSCSVMHEALHNHYTQKSLSLSPG 

Table 2A provides a summary of the SEQ ID NOS: for the CDR regions (“CDR1,” “CDR2,” and “CDR3”) of heavy and light chains of monoclonal antibodies that bind to human ATβH.

TABLE 2A Sequence Identifiers for CDR Regions of Human Anti-ATβH Antibodies Light Chain Heavy Chain Variable Region Variable Region Clones CDR1 CDR2  CDR3 CDR1 CDR2  CDR3 TPP2009 21 26 31 36 41 46 TPP2015 22 27 32 37 42 47 TPP2016 23 28 33 38 43 48 TPP2019 24 29 34 39 44 49 TPP2803 25 30 35 40 45 50

Table 2B provides sequences of the SEQ ID NOS: for the CDR regions (“CDR1,” “CDR2,” and “CDR3”) of heavy and light chains of monoclonal antibodies that bind to human ATβH.

TABLE 2B Sequences for CDR Regions of Human  Anti-ATβH Antibodies Sequence- Amino Acid Clone CDR Identifier Sequence TPP2009 LCDR1 SEQ ID NO: 21 QGDSLRSYYAS TPP2015 LCDR1 SEQ ID NO: 22 RASQSVSSSYLA TPP2016 LCDR1 SEQ ID NO: 23 RASQNINRNLA TPP2019 LCDR1 SEQ ID NO: 24 RASQRVSSSYLT TPP2803 LCDR1 SEQ ID NO: 25 QGDSLRSYYAS TPP2009 LCDR2 SEQ ID NO: 26 GKNNRPS TPP2015 LCDR2 SEQ ID NO: 27 GASSRAT TPP2016 LCDR2 SEQ ID NO: 28 TASTRAP TPP2019 LCDR2 SEQ ID NO: 29 GASSRAT TPP2803 LCDR2 SEQ ID NO: 30 GKNNRPS TPP2009 LCDR3 SEQ ID NO: 31 NSRDSSGNHLV TPP2015 LCDR3 SEQ ID NO: 32 QQYGSSRT TPP2016 LCDR3 SEQ ID NO: 33 QQYASPPRT TPP2019 LCDR3 SEQ ID NO: 34 QQYDSTPPLT TPP2803 LCDR3 SEQ ID NO: 35 NSRDSSGNHLV TPP2009 HCDR1 SEQ ID NO: 36 AYRMG TPP2015 HCDR1 SEQ ID NO: 37 KYKMD TPP2016 HCDR1 SEQ ID NO: 38 KYRMD TPP2019 HCDR1 SEQ ID NO: 39 RYAMY TPP2803 HCDR1 SEQ ID NO: 40 SYRMS TPP2009 HCDR2 SEQ ID NO: 41 RIYSSGGRTRYADSVKG TPP2015 HCDR2 SEQ ID NO: 42 RIGPSGGKTM YADSVKG TPP2016 HCDR2 SEQ ID NO: 43 RIGPSGGKTT YADSVKG TPP2019 HCDR2 SEQ ID NO: 44 RISPSGGKTH YADSVKG TPP2803 HCDR2 SEQ ID NO: 45 RIYSSGGRTR YADSVKG TPP2009 HCDR3 SEQ ID NO: 46 AREKASDLSGSFSEALDY TPP2015 HCDR3 SEQ ID NO: 47 AREKASDLSG TYSEALDY TPP2016 HCDR3 SEQ ID NO: 48 AREKTSDLSG SYSEALDY TPP2019 HCDR3 SEQ ID NO: 49 ARLSQTGYYP HYHYYGMDV TPP2803 HCDR3 SEQ ID NO: 50 AREKASDLSG SFSEALDY

In at least some possible embodiments, an isolated monoclonal antibody is provided that binds to human ATβH, wherein the antibody comprises a CDR3 comprising an amino acid sequence of any one of SEQ ID NOS: 46-50. These CDR3s are from a heavy chain of the antibodies identified during panning and screening.

In a further embodiment, this antibody further comprises: (a) a CDR1 comprising an amino acid sequence selected from the group consisting of SEQ ID NOS: 36-40; (b) a CDR2 comprising an amino acid sequence selected from the group consisting of SEQ ID NOS: 41-45; or (c) both a CDR1 comprising an amino acid sequence selected from the group consisting of SEQ ID NOS: 36-40 and a CDR2 comprising an amino acid sequence selected from the group consisting of SEQ ID NOS: 41-45.

In at least some possible embodiments, antibodies share a CDR3 from one of the light chains of the antibodies identified during panning and screening. Thus, also provided is an isolated monoclonal antibody, wherein said antibody binds to ATβH and inhibits anticoagulant activity, wherein said antibody comprises a CDR3 comprising an amino acid sequence selected from the group consisting of SEQ ID NOS: 31-35. In further embodiments, the antibody further comprises (a) a CDR1 comprising an amino acid sequence selected from the group consisting of SEQ ID NOS: 21-25, (b) a CDR2 comprising an amino acid sequence selected from the group consisting of SEQ ID NOS: 26-30, or (c) both a CDR1 comprising an amino acid sequence selected from the group consisting of SEQ ID NOS: 21-25 and a CDR2 comprising an amino acid sequence selected from the group consisting of SEQ ID NOS: 26-30.

In at least some possible embodiments, the antibody comprises a CDR3 from a heavy chain and a light chain of the antibodies identified from screening and panning. Provided is an isolated monoclonal antibody, wherein said antibody binds to ATβH and inhibits anticoagulant activity, wherein said antibody comprises a CDR3 comprising an amino acid sequence selected from the group consisting of SEQ ID NOS: 46-50 and a CDR3 comprising an amino acid sequence selected from the group consisting of SEQ ID NOS: 31-35. In a further embodiment, the antibody further comprises: (a) a CDR1 comprising an amino acid sequence selected from the group consisting of SEQ ID NOS: 36-40; (b) a CDR2 comprising an amino acid sequence selected from the group consisting of SEQ ID NOS: 41-45; (c) a CDR1 comprising an amino acid sequence selected from the group consisting of SEQ ID NOS: 21-25; and/or (d) a CDR2 comprising an amino acid sequence selected from the group consisting of SEQ ID NOs: 26-30.

In some embodiments, the antibody comprises heavy and light chain variable regions comprising:

-   -   (a) a light chain variable region comprising an amino acid         sequence comprising SEQ ID NOS: 21, 26, and 31 and a heavy chain         variable region comprising an amino acid sequence comprising SEQ         ID NOS: 36, 41, and 46;     -   (b) a light chain variable region comprising an amino acid         sequence comprising SEQ ID NOS: 22, 27, and 32 and a heavy chain         variable region comprising an amino acid sequence comprising SEQ         ID NOS: 37, 42, and 47;     -   (c) a light chain variable region comprising an amino acid         sequence comprising SEQ ID NOS: 23, 28, and 33 and a heavy chain         variable region comprising an amino acid sequence comprising SEQ         ID NOS: 38, 43, and 48;     -   (d) a light chain variable region comprising an amino acid         sequence comprising SEQ ID NOS: 24, 29, and 34 and a heavy chain         variable region comprising an amino acid sequence comprising SEQ         ID NOS: 39, 44, and 49;     -   (e) a light chain variable region comprising an amino acid         sequence comprising SEQ ID NOS: 25, 30, and 35 and a heavy chain         variable region comprising an amino acid sequence comprising SEQ         ID NOS: 40, 45, and 50.

Also provided is an isolated monoclonal antibody that binds to AtβH and inhibits anticoagulant activity, wherein said antibody comprises an amino acid sequence having at least about 89%, about 90%, about 91%, about 92%, about 93%, about 94%, about 95%, about 96%, about 97%, about 98%, about 99%, or about 99.5% identity to an amino acid sequence selected from the group consisting of the amino acid sequences set forth in SEQ ID NOS: 1-10.

The antibody can be species specific or can cross react with multiple species. In some embodiments, the antibody can specifically react or cross react with ATβH of human, mouse, rat, rabbit, guinea pig, monkey, pig, dog, cat or other mammalian species.

The antibody can be of any of the various classes of antibodies, such as without limitation an IgG1, an IgG2, an IgG3, an IgG4, an IgM, an IgA1, an IgA2, a secretory IgA, and IgD, and an IgE antibody.

In one embodiment, provided is an isolated fully human monoclonal antibody to human ATIII.

Optimized Variants of Anti-ATβH Antibodies

In some embodiments, the antibodies can be panned, screened and optimized, for example to increase affinity to ATβH, to further decrease any affinity to ATα, to improve cross-reactivity to different species, or to improve blocking activity of ATβH. Such optimization can be performed for example by utilizing site saturation mutagenesis of the CDRs or amino acid residues in close proximity to the CDRs, i.e. about 3 or 4 residues adjacent to the CDRs, of the antibodies.

Also provided are monoclonal antibodies that may have increased or high affinity to ATβH. In some embodiments, the anti-ATβH antibodies may have a binding affinity of at least about 10⁸M⁻¹, in some other embodiments may have at least about 10⁹M⁻¹, about 10¹⁰M⁻¹, about 10¹¹M⁻¹ or greater, e.g., up to about 10¹³M⁻¹ or greater.

In some embodiments, additional amino acid modifications can be introduced to reduce divergence from the germ line sequence. In other embodiments, amino acid modifications can be introduced to facilitate antibody production for large scale production processes.

In some embodiments, provided are isolated anti-ATβH monoclonal antibodies that specifically bind to human ATβ, which antibodies may comprise one or more amino acid modifications. In some embodiments, the antibody may comprise about 1, about 2, about 3, about 4, about 5, about 6, about 7, about 8, about 9, about 10, about 11, about 12, about 13, about 14, about 15, about 16, about 17, about 18, about 19, or about 20 or more modifications.

Epitopes

Also provided is an isolated monoclonal antibody that can bind to a predicted epitope of human ATβH, wherein the epitope comprises one or more of residues from human ATβH as shown in FIG. 11.

In some embodiments, the epitope comprises the N135 site of human ATβH. In other embodiments, the site can comprise part of the amino acid residue sequence of RCL loop of human ATβH.

Also provided are antibodies that can compete with any of the antibodies described herein for binding to human ATβH. For example, such a competing antibody can bind to one or more epitopes described above.

Nucleic Acids, Vectors and Host Cells

Also provided are isolated nucleic acid molecules encoding any of the monoclonal antibodies described herein. Thus, provided is an isolated nucleic acid molecule encoding an antibody that binds to human ATβH. Table 3 shows the nucleotide sequences of some anti-ATβH antibodies.

TABLE 3 Nucleotide sequence of anti-ATβH antibodies. Light Chain Heavy Chain TPP- GCACAGAGCGTCTTGA GAAGTTCAATTGTTAGAGTCTGGTGGCG 2009 CTCAGGACCCTGCTGT GTCTTGTTCAGCCTGGTGGTTCTTTACG GTCTGTGGCCTTGGGA TCTTTCTTGCGCTGCTTCCGGATTCACT CAGACAGTCAGGATC TTCTCTGCTTACCGTATGGGTTGGGTTC ACATGCCAAGGAGAC GCCAAGCTCCTGGTAAAGGTTTGGAGTG AGCCTCAGAAGCTATT GGTTTCTCGTATCTATTCTTCTGGTGGC ATGCAAGCTGGTACCA CGTACTCGTTATGCTGACTCCGTTAAAG GCAGAAGCCAGGACA GTCGCTTCACTATCTCTAGAGACAACTC GGCCCCTGTACTTGTC TAAGAATACTCTCTACTTGCAGATGAAC ATCTATGGTAAAAACA AGCTTAAGGGCTGAGGACACGGCCGTGT ACCGGCCCTCAGGGAT ATTACTGTGCGAGAGAGAAAGCGTCGGA CCCAGACCGATTCTCT TCTATCGGGGAGTTTTTCTGAGGCCCTT GGCTCCAGCTCAGGAA GACTACTGGGGCCAGGGAACCCTGGTCA ACACAGCTTCCTTGAC CCGTCTCAAGCGCCTCCACCAAGGGCCC CATCACTGGGGCTCAG ATCGGTCTTCCCGCTAGCACCCAGCAGC GCGGAAGATGAGGCT AAGAGCACCAGCGGCGGAACAGCCGCCC GACTATTACTGTAACT TGGGCTGCCTGGTGAAAGACTACTTCCC CCCGGGACAGCAGTG CGAGCCCGTGACCGTGTCCTGGAACTCT GTAACCATCTGGTATT GGCGCCCTGACCAGCGGAGTGCATACCT CGGCGGAGGGACCAA TCCCCGCCGTGCTGCAGAGCAGCGGCCT GCTGACCGTCCTAGGT GTACAGCCTGAGCAGCGTGGTGACAGTG CAGCCCAAGGCTGCCC CCCAGCAGCAGCCTGGGAACCCAGACCT CCTCGGTCACTCTGTT ACATCTGCAACGTGAACCACAAGCCCAG CCCGCCCTCCTCTGAG CAACACCAAGGTGGACAAGAAGGTGGA GAGCTTCAAGCCAACA ACCCAAGAGCTGCGACAAGACCCACAC AGGCCACACTAGTGTG CTGTCCCCCCTGCCCTGCCCCTGAACTG TCTGATCAGTGACTTC CTGGGCGGACCCAGCGTGTTCCTGTTCC TACCCGGGAGCTGTGA CCCCAAAGCCCAAGGACACCCTGATGAT CAGTGGCCTGGAAGG CAGCCGGACCCCCGAAGTGACCTGCGTG CAGATGGCAGCCCCGT GTGGTGGACGTGTCCCACGAGGACCCAG CAAGGCGGGAGTGGA AAGTGAAGTTTAATTGGTACGTGGACGG GACCACCAAACCCTCC CGTGGAAGTGCATAACGCCAAGACCAA AAACAGAGCAACAAC GCCCAGAGAGGAACAGTACAACAGCAC AAGTACGCGGCCAGC CTACCGGGTGGTGTCCGTGCTGACCGTG AGCTACCTGAGCCTGA CTGCACCAGGACTGGCTGAACGGCAAA CGCCCGAGCAGTGGA GAGTACAAGTGCAAGGTCTCCAACAAG AGTCCCACAGAAGCTA GCCCTGCCTGCCCCCATCGAGAAAACCA CAGCTGCCAGGTCACG TCAGCAAGGCCAAGGGCCAGCCCCGCG CATGAAGGGAGCACC AGCCTCAGGTGTACACACTGCCCCCCAG GTGGAGAAGACAGTG CCGGGATGAGCTGACCAAGAACCAGGT GCCCCTGCAGAATGCT GTCCCTGACCTGTCTGGTGAAAGGCTTC CT TACCCCAGCGATATCGCCGTGGAATGGG (SEQ ID NO: 11) AGAGCAACGGCCAGCCCGAGAACAATT ACAAGACCACCCCCCCTGTGCTGGACAG CGACGGCTCATTCTTCCTGTACTCCAAG CTGACCGTGGACAAGAGCCGGTGGCAG CAGGGCAACGTGTTCAGCTGCAGCGTGA TGCACGAGGCCCTGCACAATCACTACAC CCAGAAGTCCCTGAGCCTGAGCCCCGGC (SEQ ID NO: 12) TPP- GCACAAGACATCCAG GAAGTTCAATTGTTAGAGTCTGGTGGCG 2015 ATGACCCAGTCTCCAG GTCTTGTTCAGCCTGGTGGTTCTTTACG GCACCCTGTCTTTGTC TCTTTCTTGCGCTGCTTCCGGATTCACT TCCAGGGGAAAGAGC TTCTCTAAGTACAAGATGGATTGGGTTC CACCCTCTCCTGCAGG GCCAAGCTCCTGGTAAAGGTTTGGAGTG GCCAGTCAGAGTGTTA GGTTTCTCGTATCGGTCCTTCTGGTGGC GCAGCAGCTACTTAGC AAGACTATGTATGCTGACTCCGTTAAAG CTGGTACCAGCAGAA GTCGCTTCACTATCTCTAGAGACAACTC ACCTGGCCAGGCTCCC TAAGAATACTCTCTACTTGCAGATGAAC AGGCTCCTCATCTATG AGCTTAAGGGCTGAGGACACGGCCGTGT GTGCATCCAGCAGGGC ATTACTGTGCGAGAGAGAAAGCGTCGGA CACTGGCATCCCAGAC TCTATCGGGGACTTATTCTGAGGCCCTT AGGTTCAGTGGCAGTG GACTACTGGGGCCAGGGAACCCTGGTCA GGTCTGGGACAGACTT CCGTCTCAAGCGCCTCCACCAAGGGCCC CACTCTCACCATCAGC ATCGGTCTTCCCGCTAGCACCCAGCAGC AGACGGAGCCTGAAG AAGAGCACCAGCGGCGGAACAGCCGCCC ATTTTGCAGTGTATTA TGGGCTGCCTGGTGAAAGACTACTTCCC CTGTCAGCAGTATGGT CGAGCCCGTGACCGTGTCCTGGAACTCT AGCTCAACGTTCGGCC GGCGCCCTGACCAGCGGAGTGCATACCT AAGGGACCAAGGTGG TCCCCGCCGTGCTGCAGAGCAGCGGCCT AAATCAGACGAACTGT GTACAGCCTGAGCAGCGTGGTGACAGTG GGCTGCAATCTGTCTT CCCAGCAGCAGCCTGGGAACCCAGACCT CATCTTCCCGCCATCT ACATCTGCAACGTGAACCACAAGCCCAG GATGAGCAGTTGAAAT CAACACCAAGGTGGACAAGAAGGTGGA CTGGAACTGCCTCTGT ACCCAAGAGCTGCGACAAGACCCACAC TGTGTGCCTGCTGAAT CTGTCCCCCCTGCCCTGCCCCTGAACTG AACTTCTATCCCAGAG CTGGGCGGACCCAGCGTGTTCCTGTTCC AGGCCAAAGTACAGT CCCCAAAGCCCAAGGACACCCTGATGAT GGAAGGTGGATAACG CAGCCGGACCCCCGAAGTGACCTGCGTG CCCTCCAATCGGGTAA GTGGTGGACGTGTCCCACGAGGACCCAG CTCCCAGGAGAGTGTC AAGTGAAGTTTAATTGGTACGTGGACGG ACAGAGCAGGACAGC CGTGGAAGTGCATAACGCCAAGACCAA AAGGACAGCACCTAC GCCCAGAGAGGAACAGTACAACAGCAC AGCCTCAGCAGCACCC CTACCGGGTGGTGTCCGTGCTGACCGTG TGACGCTGAGCAAAG CTGCACCAGGACTGGCTGAACGGCAAA CAGACTACGAGAAAC GAGTACAAGTGCAAGGTCTCCAACAAG ACAAAGTCTACGCCTG GCCCTGCCTGCCCCCATCGAGAAAACCA CGAAGTCACCCATCAG TCAGCAAGGCCAAGGGCCAGCCCCGCG GGCCTGAGCTCGCCCG AGCCTCAGGTGTACACACTGCCCCCCAG TCACAAAGAGCTTCAA CCGGGATGAGCTGACCAAGAACCAGGT CAGGGGAGAGTGT GTCCCTGACCTGTCTGGTGAAAGGCTTC (SEQ ID NO: 13) TACCCCAGCGATATCGCCGTGGAATGGG AGAGCAACGGCCAGCCCGAGAACAATT ACAAGACCACCCCCCCTGTGCTGGACAG CGACGGCTCATTCTTCCTGTACTCCAAG CTGACCGTGGACAAGAGCCGGTGGCAG CAGGGCAACGTGTTCAGCTGCAGCGTGA TGCACGAGGCCCTGCACAATCACTACAC CCAGAAGTCCCTGAGCCTGAGCCCCGGC (SEQ ID NO: 14) TPP- GCACAAGACATCCAG GAAGTTCAATTGTTAGAGTCTGGTGGCG 2016 ATGACCCAGTCTCCAG GTCTTGTTCAGCCTGGTGGTTCTTTACG CCACCCTGTCTGTGTC TCTTTCTTGCGCTGCTTCCGGATTCACT TCCAGGGGAAAGAGC TTCTCTAAGTACCGTATGGATTGGGTTC CACCCTCTCCTGCAGG GCCAAGCTCCTGGTAAAGGTTTGGAGTG GCCAGTCAGAATATTA GGTTTCTCGTATCGGTCCTTCTGGTGGC ATAGAAACTTGGCCTG AAGACTACTTATGCTGACTCCGTTAAAG GTACCAGCAGAAGCCT GTCGCTTCACTATCTCTAGAGACAACTC GGCCGGGCTCCCAGAC TAAGAATACTCTCTACTTGCAGATGAAC TCCTCATCCATACCGC AGCTTAAGGGCTGAGGACACGGCCGTGT ATCCACTAGGGCCCCT ATTACTGTGCGAGAGAGAAAACGTCGGA GGTGTCCCAGTCAGGA TCTATCGGGGAGTTATTCTGAGGCCCTT TCACTGGCAGTGGGTC GACTACTGGGGCCAGGGAACCCTGGTCA TGGAACAGAGTTCACT CCGTCTCAAGCGCCTCCACCAAGGGCCC CTCACCATCAGCAGCC ATCGGTCTTCCCGCTAGCACCCAGCAGC TGGAACCTGAAGATTT AAGAGCACCAGCGGCGGAACAGCCGCCC TGCAGTGTATTTCTGT TGGGCTGCCTGGTGAAAGACTACTTCCC CAGCAGTATGCTAGCC CGAGCCCGTGACCGTGTCCTGGAACTCT CACCTCGGACGTTCGG GGCGCCCTGACCAGCGGAGTGCATACCT CCAAGGGACCAAGGT TCCCCGCCGTGCTGCAGAGCAGCGGCCT GGAAATCAAGCGAAC GTACAGCCTGAGCAGCGTGGTGACAGTG TGTGGCTGCACCATCT CCCAGCAGCAGCCTGGGAACCCAGACCT GTCTTCATCTTCCCGC ACATCTGCAACGTGAACCACAAGCCCAG CATCTGATGAGCAGTT CAACACCAAGGTGGACAAGAAGGTGGA GAAATCTGGAACTGCC ACCCAAGAGCTGCGACAAGACCCACAC TCTGTTGTGTGCCTGC CTGTCCCCCCTGCCCTGCCCCTGAACTG TGAATAACTTCTATCC CTGGGCGGACCCAGCGTGTTCCTGTTCC CAGAGAGGCCAAAGT CCCCAAAGCCCAAGGACACCCTGATGAT ACAGTGGAAGGTGGA CAGCCGGACCCCCGAAGTGACCTGCGTG TAACGCCCTCCAATCG GTGGTGGACGTGTCCCACGAGGACCCAG GGTAACTCCCAGGAG AAGTGAAGTTTAATTGGTACGTGGACGG AGTGTCACAGAGCAG CGTGGAAGTGCATAACGCCAAGACCAA GACAGCAAGGACAGC GCCCAGAGAGGAACAGTACAACAGCAC ACCTACAGCCTCAGCA CTACCGGGTGGTGTCCGTGCTGACCGTG GCACCCTGACGCTGAG CTGCACCAGGACTGGCTGAACGGCAAA CAAAGCAGACTACGA GAGTACAAGTGCAAGGTCTCCAACAAG GAAACACAAAGTCTA GCCCTGCCTGCCCCCATCGAGAAAACCA CGCCTGCGAAGTCACC TCAGCAAGGCCAAGGGCCAGCCCCGCG CATCAGGGCCTGAGCT AGCCTCAGGTGTACACACTGCCCCCCAG CGCCCGTCACAAAGAG CCGGGATGAGCTGACCAAGAACCAGGT CTTCAACAGGGGAGAG GTCCCTGACCTGTCTGGTGAAAGGCTTC TGT  TACCCCAGCGATATCGCCGTGGAATGGG (SEQ ID NO: 15) AGAGCAACGGCCAGCCCGAGAACAATT ACAAGACCACCCCCCCTGTGCTGGACAG CGACGGCTCATTCTTCCTGTACTCCAAG CTGACCGTGGACAAGAGCCGGTGGCAG CAGGGCAACGTGTTCAGCTGCAGCGTGA TGCACGAGGCCCTGCACAATCACTACAC CCAGAAGTCCCTGAGCCTGAGCCCCGGC (SEP ID NO: 16) TPP- GCACAAGACATCCAG GAAGTTCAATTGTTAGAGTCTGGTGGCG 2019 ATGACCCAGTCTCCAG GTCTTGTTCAGCCTGGTGGTTCTTTACG CCACCCTGTCTTTGTC TCTTTCTTGCGCTGCTTCCGGATTCACT TCCAGGGGAAAGAGC TTCTCTCGTTACGCTATGTATTGGGTTC CACCCTCTCCTGCAGG GCCAAGCTCCTGGTAAAGGTTTGGAGTG GCCAGTCAGCGTGTTA GGTTTCTCGTATCTCTCCTTCTGGTGGC GCAGCAGCTACTTAAC AAGACTCATTATGCTGACTCCGTTAAAG CTGGTACCAGCAGAA GTCGCTTCACTATCTCTAGAGACAACTC ACCTGGCCAGGCTCCC TAAGAATACTCTCTACTTGCAGATGAAC AGGCTCCTCATCTATG AGCTTAAGGGCTGAGGACACGGCCGTGT GTGCATCCAGCAGGGC ATTACTGTGCGAGACTGTCTCAAACTGG CACTGGCATCCCAGAC TTATTACCCTCACTACCACTACTACGGT AGGTTCAGTGGCAGTG ATGGACGTCTGGGGCCAAGGGACCACGG GGTCTGGGACAGACTT TCACCGTCTCAAGCGCCTCCACCAAGGG CACTCTCACCATCAGC CCCATCGGTCTTCCCGCTAGCACCCAGC AGACTGGAGCCTGAA AGCAAGAGCACCAGCGGCGGAACAGCCG GATTTTGCAGTTTATT CCCTGGGCTGCCTGGTGAAAGACTACTT ACTGTCAGCAGTATGA CCCCGAGCCCGTGACCGTGTCCTGGAAC TAGTACGCCTCCGCTC TCTGGCGCCCTGACCAGCGGAGTGCATA ACCTTCGGCGGAGGG CCTTCCCCGCCGTGCTGCAGAGCAGCGG ACCAAGGTGGAGATC CCTGTACAGCCTGAGCAGCGTGGTGACA AAACGAACTGTGGCTG GTGCCCAGCAGCAGCCTGGGAACCCAGA CACCATCTGTCTTCAT CCTACATCTGCAACGTGAACCACAAGCC CTTCCCGCCATCTGAT CAGCAACACCAAGGTGGACAAGAAGGTG GAGCAGTTGAAATCTG GAACCCAAGAGCTGCGACAAGACCCAC GAACTGCCTCTGTTGT ACCTGTCCCCCCTGCCCTGCCCCTGAAC GTGCCTGCTGAATAAC TGCTGGGCGGACCCAGCGTGTTCCTGTT TTCTATCCCAGAGAGG CCCCCCAAAGCCCAAGGACACCCTGATG CCAAAGTACAGTGGA ATCAGCCGGACCCCCGAAGTGACCTGCG AGGTGGATAACGCCCT TGGTGGTGGACGTGTCCCACGAGGACCC CCAATCGGGTAACTCC AGAAGTGAAGTTTAATTGGTACGTGGAC CAGGAGAGTGTCACA GGCGTGGAAGTGCATAACGCCAAGACC GAGCAGGACAGCAAG AAGCCCAGAGAGGAACAGTACAACAGC GACAGCACCTACAGCC ACCTACCGGGTGGTGTCCGTGCTGACCG TCAGCAGCACCCTGAC TGCTGCACCAGGACTGGCTGAACGGCAA GCTGAGCAAAGCAGA AGAGTACAAGTGCAAGGTCTCCAACAA CTACGAGAAACACAA GGCCCTGCCTGCCCCCATCGAGAAAACC AGTCTACGCCTGCGAA ATCAGCAAGGCCAAGGGCCAGCCCCGC GTCACCCATCAGGGCC GAGCCTCAGGTGTACACACTGCCCCCCA TGAGCTCGCCCGTCAC GCCGGGATGAGCTGACCAAGAACCAGG AAAGAGCTTCAACAG TGTCCCTGACCTGTCTGGTGAAAGGCTT GGGAGAGTGT  CTACCCCAGCGATATCGCCGTGGAATGG (SEQ ID NO: 17) GAGAGCAACGGCCAGCCCGAGAACAAT TACAAGACCACCCCCCCTGTGCTGGACA GCGACGGCTCATTCTTCCTGTACTCCAA GCTGACCGTGGACAAGAGCCGGTGGCA GCAGGGCAACGTGTTCAGCTGCAGCGTG ATGCACGAGGCCCTGCACAATCACTACA CCCAGAAGTCCCTGAGCCTGAGCCCCGG C(SEQ ID NO: 18) TPP- AGCGAATTGACTCAGG GAAGTGCAGCTGCTGGAAAGCGGCGGA 2803 ACCCTGCTGTGTCTGT GGCCTGGTGCAGCCTGGCGGATCTCTGA GGCCTTGGGACAGAC GACTGAGCTGTGCCGCCAGCGGCTTCAC AGTCAGGATCACATGC CTTCAGCAGCTACAGAATGAGCTGGGTG CAAGGAGACAGCCTC CGCCAGGCCCCTGGCAAGGGACTGGAA AGAAGCTATTATGCAA TGGGTGTCCCGGATCTACAGCAGCGGCG GCTGGTACCAGCAGA GCAGAACCAGATACGCCGACAGCGTGA AGCCAGGACAGGCCC AGGGCCGGTTCACCATCTCCCGGGACAA CTGTACTTGTCATCTA CAGCAAGAACACCCTGTACCTGCAGATG TGGTAAAAACAACCG AACAGCCTGCGGGCCGAGGACACCGCC GCCCTCAGGGATCCCA GTGTACTATTGCGCCAGAGAGAAGGCCA GACCGATTCTCTGGCT GCGACCTGAGCGGCAGCTTTAGCGAGGC CCAGCTCAGGAAACA CCTGGATTATTGGGGCCAGGGCACACTC CAGCTTCCTTGACCAT GTGACCGTGTCTAGCGCCAGCACAAAGG CACTGGGGCTCAGGCG GCCCCAGCGTGTTCCCTCTGGCCCCTTG GAAGATGAGGCTGAC TAGCAGAAGCACCAGCGAGTCTACAGCC TATTACTGTAACTCCC GCCCTGGGCTGCCTCGTGAAGGACTACT GGGACAGCAGTGGTA TTCCCGAGCCCGTGACAGTGTCCTGGAA ACCATCTGGTATTCGG CTCTGGCGCCCTGACAAGCGGCGTGCAC CGGAGGGACCAAGCT ACCTTTCCAGCCGTGCTGCAGAGCAGCG GACCGTCCTAGGTCAG GCCTGTACTCTCTGAGCAGCGTCGTGAC CCCAAGGCTGCCCCCT TGTGCCCAGCAGCAACTTCGGCACCCAG CGGTCACTCTGTTCCC ACCTACACCTGTAACGTGGACCACAAGC GCCCTCCTCTGAGGAG CCAGCAACACCAAGGTGGACAAGACCG CTTCAAGCCAACAAGG TGGAACGGAAGTGCTGCGTGGAATGCCC CCACACTAGTGTGTCT CCCTTGTCCTGCCCCTCCAGTGGCTGGC GATCAGTGACTTCTAC CCTTCCGTGTTCCTGTTCCCCCCAAAGC CCGGGAGCTGTGACA CCAAGGACACCCTGATGATCAGCCGGAC GTGGCCTGGAAGGCA CCCGAAGTGACCTGCGTGGTGGTGGATG GATGGCAGCCCCGTCA TGTCCCACGAGGACCCCGAGGTGCAGTT AGGCGGGAGTGGAGA CAATTGGTACGTGGACGGCGTGGAAGTG CCACCAAACCCTCCAA CACAACGCCAAGACCAAGCCCAGAGAGG ACAGAGCAACAACAA AACAGTTCAACAGCACCTTCCGGGTGGT GTACGCGGCCAGCAG GTCCGTGCTGACCGTGGTGCATCAGGAC CTACCTGAGCCTGACG TGGCTGAACGGCAAAGAGTACAAGTGC CCCGAGCAGTGGAAG AAGGTGTCCAACAAGGGCCTGCCTGCCC TCCCACAGAAGCTACA CCATCGAGAAAACCATCAGCAAGACCA GCTGCCAGGTCACGCA AAGGCCAGCCCCGCGAGCCCCAGGTGT TGAAGGGAGCACCGT ACACACTGCCTCCAAGCCGGGAAGAGA GGAGAAGACAGTGGC TGACCAAGAACCAGGTGTCCCTGACCTG CCCTGCAGAATGCTCT TCTCGTGAAAGGCTTCTACCCCTCCGAT (SEQ ID NO: 19) ATCGCCGTGGAATGGGAGAGCAACGGC CAGCCCGAGAACAACTACAAGACCACC CCCCCCATGCTGGACAGCGCGGCTCATT CTTCCTGTACAGCAAGCTGACAGTGGAC AAGTCCCGGTGGCAGCAGGGCAACGTG TTCAGCTGCAGCGTGATGCACGAAGCCC TGCACAACCACTACACCCAGAAGTCCCT GAGCCTGAGCCCTGGC  (SEQ ID NO: 20)

In some embodiments, isolated nucleic acid molecules encode an antibody that binds to ATβH and inhibits anticoagulant activity but has minimal binding to ATα, wherein the antibody comprises a heavy chain variable region comprising an amino acid sequence selected from the group consisting of SEQ ID NOS: 2, 4, 6, 8, and 10.

In some embodiments, isolated nucleic acid molecules encode an antibody that binds to ATβH and inhibits anticoagulant activity but has minimal binding to ATα, wherein the antibody comprises a light chain variable region comprising an amino acid sequence selected from the group consisting of SEQ ID NOS: 1, 3, 5, 7, and 9.

In other embodiments, isolated nucleic acid molecules encode an antibody that binds to ATβ and inhibits anticoagulant activity of ATβ, wherein the antibody comprises a heavy chain variable region comprising an amino acid sequence selected from the group consisting of SEQ ID NOS: 2, 4, 6, 8, and 10 or a light chain variable region comprising an amino acid sequence selected from the group consisting of SEQ ID NOS: 1, 3, 5, 7, and 9 and one or more amino acid modifications in the heavy chain variable region or light chain variable region.

Further, also provided are vectors comprising the isolated nucleic acid molecules encoding any of the monoclonal antibodies described above and host cells comprising such vectors.

Methods of Preparing Antibodies to ATβH

The monoclonal antibody can be produced recombinantly by expressing a nucleotide sequence encoding the variable regions of the monoclonal antibody according to one of the present embodiments in a host cell. With the aid of an expression vector, a nucleic acid containing the nucleotide sequence can be transfected and expressed in a host cell suitable for the production. Accordingly, an exemplary method for producing a monoclonal antibody that binds with human ATβH can comprise: (a) transfecting a nucleic acid molecule encoding a monoclonal antibody into a host cell; (b) culturing the host cell so to express the monoclonal antibody in the host cell, and (c) optionally isolating and purifying the produced monoclonal antibody, wherein the nucleic acid molecule comprises a nucleotide sequence encoding a monoclonal antibody.

In one example, to express the antibodies, or antibody fragments thereof, DNAs encoding partial or full-length light and heavy chains obtained by standard molecular biology techniques are inserted into expression vectors such that the genes are operatively linked to transcriptional and translational control sequences. In this context, the term “operatively linked” refers to an antibody gene that is ligated into a vector such that transcriptional and translational control sequences within the vector serve their intended function of regulating the transcription and translation of the antibody gene. The expression vector and expression control sequences are chosen to be compatible with the expression host cell used. The antibody light chain gene and the antibody heavy chain gene can be inserted into separate vectors or, alternatively, both genes are inserted into the same expression vector. The antibody genes are inserted into the expression vector by standard methods (e.g., ligation of complementary restriction sites on the antibody gene fragment and vector, or blunt end ligation if no restriction sites are present). The light and heavy chain variable regions of the antibodies described herein can be used to create full-length antibody genes of any antibody isotype by inserting them into expression vectors already encoding heavy chain constant and light chain constant regions of the desired isotype such that the VH segment is operatively linked to the CH segment(s) within the vector and the VL segment is operatively linked to the CL segment within the vector.

Additionally, or alternatively, the recombinant expression vector can encode a signal peptide that facilitates secretion of the antibody chain from a host cell. The antibody chain gene can be cloned into the vector such that the signal peptide is linked in-frame to the amino terminus of the antibody chain gene. The signal peptide can be an immunoglobulin signal peptide or a heterologous signal peptide (i.e., a signal peptide from a non-immunoglobulin protein). In addition to the antibody chain encoding genes, the recombinant expression vectors carry regulatory sequences that control the expression of the antibody chain genes in a host cell. The term “regulatory sequence” includes promoters, enhancers, and other expression control elements (e.g., polyadenylation signals) that control the transcription or translation of the antibody chain genes. Such regulatory sequences are described, for example, in Goeddel; Gene Expression Technology. Methods in Enzymology 185, Academic Press, San Diego, Calif. (1990). It will be appreciated by those skilled in the art that the design of the expression vector, including the selection of regulatory sequences can depend on such factors as the choice of the host cell to be transformed, the level of expression of protein desired, etc. Examples of regulatory sequences for mammalian host cell expression include viral elements that direct high levels of protein expression in mammalian cells, such as promoters and/or enhancers derived from cytomegalovirus (CMV), Simian Virus 40 (SV40), adenovirus, (e.g., the adenovirus major late promoter (AdMLP)) and polyoma. Alternatively, non-viral regulatory sequences can be used, such as the ubiquitin promoter or β-globin promoter.

In addition to the antibody chain genes and regulatory sequences, the recombinant expression vectors can carry additional sequences, such as sequences that regulate replication of the vector in host cells (e.g., origins of replication) and selectable marker genes. The selectable marker gene facilitates selection of host cells into which the vector has been introduced (see, e.g., U.S. Pat. Nos. 4,399,216; 4,634,665; and 5,179,017, all by Axel et al.). For example, typically the selectable marker gene confers resistance to drugs, such as G418, hygromycin or methotrexate, on a host cell into which the vector has been introduced. Examples of selectable marker genes include the dihydrofolate reductase (DHFR) gene (for use in dhfr-host cells with methotrexate selection/amplification) and the neo gene (for G418 selection).

For expression of the light and heavy chains, the expression vector(s) encoding the heavy and light chains is transfected into a host cell by standard techniques. The various forms of the term “transfection” encompasses a wide variety of techniques commonly used for the introduction of exogenous DNA into a prokaryotic or eukaryotic host cell, e.g., electroporation, calcium-phosphate precipitation, DEAE-dextran transfection, and the like. Although it is theoretically possible to express the antibodies in either prokaryotic or eukaryotic host cells, expression of antibodies in eukaryotic cells, including mammalian host cells, is typical because such eukaryotic cells, and in particular mammalian cells, are more likely than prokaryotic cells to assemble and secrete a properly folded and immunologically active antibody. Examples of mammalian host cells for expressing the recombinant antibodies include Chinese Hamster Ovary (CHO cells) (including dhfr-CHO cells, described in Urlaub and Chasin, (1980) Proc. Natl. Acad. Sci. USA 77:4216-4220, used with a DHFR selectable marker, e.g., as described in R. J. Kaufman and P. A. Sharp (1982) Mol. Biol. 159:601-621), NSO myeloma cells, COS cells, HKB11 cells and SP2 cells. When recombinant expression vectors encoding antibody genes are introduced into mammalian host cells, the antibodies are produced by culturing the host cells for a period of time sufficient to allow for expression of the antibody in the host cells or secretion of the antibody into the culture medium in which the host cells are grown. Antibodies can be recovered from the culture medium using standard protein purification methods, such as ultrafiltration, size exclusion chromatography, ion exchange chromatography and centrifugation.

Use of Partial Antibody Sequences to Express Intact Antibodies

Antibodies interact with target antigens predominantly through amino acid residues that are located in the six heavy and light chain CDRs. For this reason, the amino acid sequences within CDRs are more diverse between individual antibodies than sequences outside of CDRs. Because CDR sequences are responsible for most antibody-antigen interactions, it is possible to express recombinant antibodies that mimic the properties of specific naturally occurring antibodies by constructing expression vectors that include CDR sequences from the specific naturally occurring antibody grafted onto framework sequences from a different antibody with different properties (see, e.g., Riechmann, L. et al., 1998, Nature 332:323-327; Jones, P. et al., 1986, Nature 321:522-525; and Queen, C. et al., 1989, Proc. Natl. Acad. Sci. U.S.A. 86:10029-10033). Such framework sequences can be obtained from public DNA databases that include germline antibody gene sequences. These germline sequences will differ from mature antibody gene sequences because they will not include completely assembled variable genes, which are formed by V(D)J joining during B cell maturation. It is not necessary to obtain the entire DNA sequence of a particular antibody in order to recreate an intact recombinant antibody having binding properties similar to those of the original antibody (see WO 99/45962).

Partial heavy and light chain sequence spanning the CDR regions is typically sufficient for this purpose. The partial sequence is used to determine which germline variable and joining gene segments contributed to the recombined antibody variable genes. The germline sequence is then used to fill in missing portions of the variable regions. Heavy and light chain leader sequences are cleaved during protein maturation and do not contribute to the properties of the final antibody. For this reason, the corresponding germline leader sequence is used for expression constructs. To add missing sequences, cloned cDNA sequences can be combined with synthetic oligonucleotides by ligation or PCR amplification. Alternatively, the entire variable region can be synthesized as a set of short, overlapping, oligonucleotides and combined by PCR amplification to create an entirely synthetic variable region clone. This process has advantages such as elimination or inclusion or particular restriction sites, or optimization of particular codons. The nucleotide sequences of heavy and light chain transcripts are used to design an overlapping set of synthetic oligonucleotides to create synthetic V sequences with identical amino acid coding capacities as the natural sequences. The synthetic heavy and light chain sequences can differ from the natural sequences. For example, strings of repeated nucleotide bases are interrupted to facilitate oligonucleotide synthesis and PCR amplification; and optimal translation initiation sites are incorporated according to Kozak's rules (Kozak, 1991, J. Biol. Chem. 266:19867-19870); and restriction sites are engineered upstream or downstream of the translation initiation sites. For both the heavy and light chain variable regions, the optimized coding, and corresponding non-coding, strand sequences are broken down into 30-50 nucleotide sections at approximately the midpoint of the corresponding non-coding oligonucleotide. For each chain, the oligonucleotides can be assembled into overlapping double stranded sets that span segments of 150-400 nucleotides. The pools are then used as templates to produce PCR amplification products of 150-400 nucleotides.

Typically, a single variable region oligonucleotide set will be broken down into two pools which are separately amplified to generate two overlapping PCR products. These overlapping products are then combined by PCR amplification to form the complete variable region. It can also be desirable to include an overlapping fragment of the heavy or light chain constant region in the PCR amplification to generate fragments that can easily be cloned into the expression vector constructs. The reconstructed heavy and light chain variable regions are then combined with cloned promoter, translation initiation, constant region, 3′ untranslated, polyadenylation, and transcription termination sequences to form expression vector constructs. The heavy and light chain expression constructs can be combined into a single vector, co-transfected, serially transfected, or separately transfected into host cells which are then fused to form a host cell expressing both chains. In another aspect, the structural features of a human anti-ATβH antibody are used to create structurally related human anti-ATβH antibodies that retain the function of binding to ATβ. For example, one or more CDRs of the specifically identified heavy and light chain regions of the monoclonal antibodies can be combined recombinantly with known human framework regions and CDRs to create additional, recombinantly-engineered, human anti-ATβH antibodies.

Pro-Coagulant Efficacy of Anti-ATβH mAbs

Pro-coagulant efficacy of anti-ATβH mAbs was investigated using various assays.

Table 4 shows pro-coagulant efficacy of Anti-ATβH mAbs TPP2009 and TPP2803 in plasma from various animal species in the FXa-activated clotting assay.

TABLE 4 Pro-coagulant efficacy of TPP2009 and TPP2803 in plasma from various animal species. Normal Plasma HEM A Plasma HEM A Plasma (EC₅₀ nM) (EC₅₀ in nM) (EC₅₀ in nM) Species 2009 2803 2009 2803 2009 FXa-Activated Clotting Assay dPT Human 10.5 2.4 4.7 2.7  9.0 Mouse NDR ND ND ND NDR Rat NDR ND ND ND ND Rabbit 25.7 ND 10.5  ND NDR Beagle NDR ND ND ND NDR Cyno 21.5 ND 4.3 ND 13.9 NDR: no dose response, ND: not determined, dPT: diluted prothrombin time, HEM-A: Hemophilia A plasma.

Anti-ATβH mAbs TPP2009 and TPP2803 both exhibited pro-coagulant efficacy in human normal plasma and hemophilia A plasma in the FXa-activated clotting assay. Specifically, TPP2009 exhibited pro-coagulant efficacy in human normal plasma and hemophilia A plasma in the FXa-activated clotting assay with EC₅₀'s of 10.5 nM and 4.7 nM, respectively. TPP2803 exhibited pro-coagulant efficacy in human normal plasma and hemophilia A plasma in the FXa-activated clotting assay with EC₅₀'s of 2.4 and 2.7 nM, respectively.

In addition, Anti-ATβH mAb TPP2803 exhibited dose-dependent shortening of the clotting time in both normal human plasma and hemophilia patient plasma using the FXa activated clotting assay, as shown in FIG. 12. CT: clotting time, HEM-A: Hemophilia A plasma.

The heparinized rabbit bleeding model outlined in FIG. 13 was employed to demonstrate in vivo pro-coagulant efficacy of Anti-ATβH mAb TPP2803. The effect of a control and TPP2803 on bleeding time before and after LMWH and compound administration in a heparinized rabbit bleeding model are shown in FIG. 14. Bleeding time after administration of LMWH and Test Article (either 3 mg/kg or 30 mg/kg TPP2803) was significantly reduced compared to bleeding time after LMWH in PBS. Delta bleeding time after administration of either Test Article (either 3 mg/kg or 30 mg/kg TPP2803), or positive control protamine sulfate, was significantly different from PBS (p≦0.05; * significance by T-test) as shown in FIG. 15. The effect of a control and TPP2803 on blood loss before and after LMWH and antibody administration is shown in FIG. 16. TPP2803 (3 mg/kg) and positive control protamine sulfate both exhibited a significant change in blood loss (*Significance by the T-test) after administration of LMWH.

Pharmaceutical Compositions

Also provided are pharmaceutical compositions comprising therapeutically effective amounts of anti-ATβH monoclonal antibody and a pharmaceutically acceptable carrier. “Pharmaceutically acceptable carrier” as used herein refers to a substance that can be added to the active ingredient to help formulate or stabilize the preparation and causes no significant adverse toxicological effects to the patient. Examples of such carriers are well known to those skilled in the art and include water, sugars such as maltose or sucrose, albumin, salts such as sodium chloride, etc. Other carriers are described for example in Remington's Pharmaceutical Sciences by E. W. Martin. Such compositions will contain a therapeutically effective amount of at least one monoclonal antibody.

Pharmaceutically acceptable carriers include sterile aqueous solutions or dispersions and sterile powders for the extemporaneous preparation of sterile injectable solutions or dispersion. The use of such media and agents for pharmaceutically active substances is known in the art. The composition is in some embodiments formulated for parenteral injection. The composition can be formulated as a solution, microemulsion, liposome, or other ordered structure suitable to high drug concentration. The carrier can be a solvent or dispersion medium containing, for example, water, ethanol, polyol (for example, glycerol, propylene glycol, and liquid polyethylene glycol, and the like), and suitable mixtures thereof. In some cases, the composition of the carrier includes isotonic agents, for example, sugars, polyalcohols such as mannitol, sorbitol, or sodium chloride.

Sterile injectable solutions can be prepared by incorporating the active compound in the required amount in an appropriate solvent with one or a combination of ingredients enumerated above, as required, followed by sterilization microfiltration. Generally, dispersions are prepared by incorporating the active compound into a sterile vehicle that contains a basic dispersion medium and the required other ingredients from those enumerated above. In the case of sterile powders for the preparation of sterile injectable solutions, some methods of preparation are vacuum drying and freeze-drying (lyophilization) that yield a powder of the active ingredient plus any additional desired ingredient from a previously sterile-filtered solution thereof.

Pharmaceutical Uses

The monoclonal antibody can be used for therapeutic purposes for treating genetic and acquired deficiencies or defects in coagulation. For example, the monoclonal antibodies in the embodiments described above can be used to block the interaction of ATβH with its substrate, which can include Factor Xa or Factor IIa. The monoclonal antibodies have therapeutic use in the treatment of disorders of hemostasis such as thrombocytopenia, platelet disorders and bleeding disorders (e.g., hemophilia A, hemophilia B and hemophilia C). Such disorders can be treated by administering a therapeutically effective amount of the anti-ATβH monoclonal antibody to a patient in need thereof. The monoclonal antibodies also have therapeutic use in the treatment of uncontrolled bleeds in indications such as trauma and hemorrhagic stroke. Thus, also provided is a method for shortening the bleeding time comprising administering a therapeutically effective amount of an anti-ATβH monoclonal antibody to a patient in need thereof.

In another embodiment, the anti-ATβH antibody can be useful as an antidote for AT treated patients, including for example wherein AT is used for the treatment of sepsis or bleeding disorder.

The antibodies can be used as monotherapy or in combination with other therapies to address a hemostatic disorder. For example, co-administration of one or more antibodies with a clotting factor such as Factor VIIa, Factor VIII or Factor IX is believed useful for treating hemophilia. In at least some embodiments, a method for treating genetic and acquired deficiencies or defects in coagulation comprises administering: (a) a first amount of a monoclonal antibody that binds to human tissue factor pathway inhibitor; and (b) a second amount of Factor VIII or Factor IX, wherein said first and second amounts together are effective for treating said deficiencies or defects. In at least some embodiments, a method for treating genetic and acquired deficiencies or defects in coagulation comprises administering: (a) a first amount of a monoclonal antibody that binds to human tissue factor pathway inhibitor; and (b) a second amount of factor VIII or Factor IX, wherein said first and second amounts together are effective for treating said deficiencies or defects, and further wherein Factor VII is not co-administered. Also provided is a pharmaceutical composition comprising a therapeutically effective amount of the combination of a monoclonal antibody and Factor VIII or Factor IX, wherein the composition does not contain Factor VII. “Factor VII” includes Factor VII and Factor VIIa. These combination therapies are likely to reduce the necessary infusion frequency of the clotting factor. By co-administration or combination therapy is meant administration of the two therapeutic drugs each formulated separately or formulated together in one composition, and, when formulated separately, administered either at approximately the same time or at different times, but over the same therapeutic period.

In some embodiments, one or more antibodies described herein can be used in combination to address a hemostatic disorder. For example, co-administration of two or more of the antibodies described herein is believed useful for treating hemophilia or other hemostatic disorder.

The pharmaceutical compositions can be parenterally administered to subjects suffering from hemophilia A or B at a dosage and frequency that can vary with the severity of the bleeding episode or, in the case of prophylactic therapy, can vary with the severity of the patient's clotting deficiency.

The compositions can be administered to patients in need as a bolus or by continuous infusion. For example, a bolus administration of an antibody as a Fab fragment can be in an amount from about 0.0025 to about 100 mg/kg body weight, about 0.025 to about 0.25 mg/kg, about 0.010 to about 0.10 mg/kg or about 0.10 to about 0.50 mg/kg. For continuous infusion, an inventive antibody present as an Fab fragment can be administered at about 0.001 to about 100 mg/kg body weight/minute, about 0.0125 to about 1.25 mg/kg/min, about 0.010 to about 0.75 mg/kg/min, about 0.010 to about 1.0 mg/kg/min, or about 0.10 to about 0.50 mg/kg/min for a period of about 1-24 hours, about 1-12 hours, about 2-12 hours, about 6-12 hours, about 2-8 hours, or about 1-2 hours. For administration of an inventive antibody present as a full-length antibody (with full constant regions), dosage amounts can be about 1-10 mg/kg body weight, about 2-8 mg/kg, or about 5-6 mg/kg. Such full-length antibodies would typically be administered by infusion extending for a period of thirty minutes to three hours. The frequency of the administration would depend upon the severity of the condition. Frequency could range from three times per week to once every two weeks to six months.

Additionally, the compositions can be administered to patients via subcutaneous injection. For example, a dose of about 10 to about 100 mg anti-ATβH antibody can be administered to patients via subcutaneous injection weekly, biweekly or monthly. As used herein, “therapeutically effective amount” means an amount of an anti-ATβH monoclonal antibody or of a combination of such antibody and Factor VIII or Factor IX that is needed to effectively increase the clotting time in vivo or otherwise cause a measurable benefit in vivo to a patient in need thereof. The precise amount will depend upon numerous factors, including the components and physical characteristics of the therapeutic composition, intended patient population, individual patient considerations, and the like, and can readily be determined by one skilled in the art.

Aspects of the present disclosure may be further understood in light of the following examples, which should not be construed as limiting the scope of the present teachings in any way.

Example 1 Human and Rabbit ATα and ATβ Purification

ATα and ATβ were purified from human and rabbit plasma by affinity chromatography on heparin-sepharose according to methods previously described (Carlson and Atencio 1982; Peterson and Blackburn 1985) at Enzyme Research laboratory (South Bend, Ind.). Briefly, the supernatant from a dextran sulphate/calcium chloride precipitation was applied to a heparin-sepharose affinity column (Pharmacia). ATα and ATβ were separated with a NaCl gradient: ATα and ATβ were eluted at 0.8 M and 1.3 M NaCl, respectively. Anion-exchange chromatography (HiTrap-Q, Pharmacia) was employed for further purification of ATβ. Purity and glycan profile of ATα and ATβ were evaluated by protein SDS-PAGE and LC-MS.

Example 2 Determination of the Number and Position of Glycans on ATα and ATβ by Mass-Spectrometry Analysis

Due to the distinct number of glycans, ATα and ATβ were differentiated based on their mass by Agilent 6520 LC-MS system which is equipped with a DUO-ESI dual electrospray ionization source or a NANO CHIPCUBE HPLC-Chip MS Cube interface, MASSHUNTER acquisition software and qualitative analysis software including BIOCONFIRM protein characterization software. Glycosylation sites were determined by a bottom-up method in which proteins are digested by trypsin and Arg-c followed by target MSMS to identify the glycosylated and mono-glycosylated peptide sequences. Data was collected in two experiments: Fragmentor voltage 175v and 430v.

Example 3 AT Antigen Biotinylation

Human and rabbit ATα and ATβ were labeled with biotins on the surface lysine residues by NHS-biotin. For lysine biotinylation, proteins were first desalted into PBS/Ca⁺⁺ buffer (Life Technologies Corporation, Carlsbad, Calif.) to remove any amines that might be inhibitory to the biotinylation reaction. Concentrations of desalted proteins were determined by OD280 on the NanoDrop. Protein were then incubated for 1 hour at room temperature (RT) with Sulfo-NHS-Biotin (Pierce Thermo Scientific, Rockford, Ill.) at the 1:5 and/or 1:3 molar ratio of AT:NHS-biotin (i.e. biotin in excess). Free biotin was removed by overnight dialysis into PBS/Ca⁺⁺ buffer. The amount of biotin in the biotinylated proteins was quantified using Biotin Quantitation Kit (Pierce Thermo Scientific, Rockford, Ill.). Biotinylated ATα and ATβ were analyzed by SDS-PAGE, and biotinylation was confirmed by Western blot analysis using streptavidin-HRP (Pierce Thermo Scientific, Rockford, Ill.) as probe. The functional activities of biotinylated AT were evaluated by FXa inhibition assay. By comparison of the biotinylated ATα and ATβ with unbiotinylated ATα and ATβ, only slight reductions in AT inhibition activity were observed after biotinylation, indicating the biotinylated ATβ and ATα prepared in this way would be representative and could be used in panning for ATβH binders as selective anti-coagulant blockers.

Example 4 Human Monoclonal Antibody Discovery by Phage Display and Panning

A four-arm panning strategy was designed to discover Fabs specifically against ATβH from a human Fab library (Dyax Fab310). The library was first depleted with biotinylated heparin/Fondaparinux-bound ATα and biotinylated ATα and then was panned against heparin/Fondaparinux-bound ATβ and biotinylated ATβ on streptavidin beads, respectively. For each round of panning, the heparin-bound ATα (ATαH) was included in the binding buffer as a competitor. To keep hATβ in active conformation (heparin bound form), heparin was added to the wash buffer in all three rounds of panning. After panning, pooled clones were screened for hATβ and hATβH specific binding and counter-screened for hATα by ELISA. These clones were also examined for differential binding to rabbit ATβ over rabbit ATα. Clones showing differential binding to both hATβH and rATβH over hATα and rATα were further subject to FXa—deinhibition assay with hATβ spike-in. Positive hits (Fabs) were reformatted into IgG1, expressed in HEK293 cells and purified by protein-A column. These purified IgG1s were extensively tested in AT-depleted human plasma and hemA patient plasma for TGA assay (Thrombin Generation Assay) and dPT (diluted Prothrombin Time) assay to measure the clotting time.

Example 5 ELISA (Enzyme-Linked Immunosorbent Assay)

2 μg/ml biotinlyated AT antigens in PBS were coated on Streptavidin Microplates (Greiner, 781997) with or without heparin (50 ug/ml, heparin-Natrium-5000, Apotheke, Fa. Ratiopharm). After overnight antigen coating at 4° C., plates were washed with PBST+/− heparin and blocked with 5% milk in PBST+/−heparin at 37° C. for one hour. After removal of blocking buffer, 20 ug/ml Fab or 4 ug/ml IgG in blocking buffer (5% milk in PBST+/−heparin) was then added to the plates and plates were incubated at room temperature for 1 hour. Plates were then washed three times. Anti-human IgG POD (Sigma, A0170) in blocking buffer was added to plates and plates were incubated at room temperature for 30 minutes. Amplex red (In vitrogen, Cat#A22170) was used for detection at 1:1000 together with H₂O₂. After 30 min incubation, plates were read at Ex535, Em 590 in a fluorescent plate reader.

Example 6 FXa De-Inhibition Assay—AT with Heparin

Heparin was incubated with ATβ or ATα to form stable ATH complexes. Antibody was then added to the ATβ H or ATα H complexes. In the meantime, 10 μl of 200 ng/ml FXa (HTI) and 20 μl of 50 μg/ml FLUOPHEN FXa fluorogenic substrate (Hyphen Biomed) were mixed in a separate plate. The antibody-ATH mixture was added to the FXa/substrate solution quickly and fluorescent kinetic measurement was started immediately at Ex360 nm and Em465 nm. All necessary dilutions is made in 100 mM NaCl, 20 mM Tris, 2.5 mM CaCl2, 0.1% BSA, 0.1% PEG8000.

Example 7 Thrombin Generation Assay (TGA) in FVIII Deficiency Human Plasma

A 1:2 serial dilution of ATβH antibody was made in HemA human plasma starting from 1 uM of final concentration to 0.015 uM. Heparin was added in each antibody solution at a final concentration of 50 nM. An 80 ul of the antibody-heparin-plasma mixture was then added to each well containing 20 ul of reconstitute PPP reagent or calibrator in a 96 well TGA plate. The plate was placed in the TGA instrument and the machine automatically dispensed 20 ul of FluCa (Fluo substrate+CaCl₂) into each well. The reaction was allowed to run 60 min. Plasma alone was used as the negative control.

Example 8 Thrombin Generation Assay (TGA) in AT-Depleted Human Plasma with Spiked-in ATα and ATβ Respectively

Antibodies were added to human AT-deficient plasma spiked with 15 nm of ATα or ATβ. Heparin was then pipetted into each reaction at a final concentration of 50 nM. 80 ul of plasma samples containing ATH-specific antibody, heparin and ATα or ATβ were added into wells of a 96 well TGA plate with 20 ul of PPP reagent or calibrator. Plates were placed in the TGA instrument, and then 20 ul of FluCa (Fluo substrate+CaCl₂) was dispensed into each well. Reactions were allowed to continue for 60 min.

Example 9 Diluted Prothrombin Time Assay (dPT) in Human hemA Plasma and AT deficient plasma

A serial dilution of anti-ATβH hmAbs was made in hemA plasma starting at 250 nM with 0.1 U/mL of heparin. The mixture of antibody, plasma and heparin was incubated at room temperature for 20-30 min. Then 50 uL of this mixture was added to a 50 uL of diluted (1/2000) recombinant human tissue factor (INNOVIN) (Dade Behring), incubated for 4 min at 37° C., followed by adding 50 uL of 25 mM CaCl2 (HEMSIL). dPT test program was set on ACL Top coagulometer with acquisition time of 360 seconds. For dTP in AT deficient plasma, ATDP was spiked in with either ATα or ATP at a final concentration of 0.2 uM with 0.1 U/ml of heparin. Anti-ATβ H mAbs was added to AT-DP/heparin/ATα or ATDP/heparin/ATβ mixtures at a final concentration of 0.25 uM and incubated at room temperature for 20-30 min. For each reaction, a 50 uL of plasma/antibody/heparin mixture was added to 50 uL of diluted (1/4000) recombinant human tissue factor (INNOVIN), incubate 4 min at 37° C., followed by adding 50 uL of 25 mM CaCl2 (HEMSIL) as above.

Example 10 Antibody Purification

Pre-washed protein A agarose beads were incubated with antibody in binding buffer (volume ratio: 1:1) with rotation overnight at 4° C. Beads were then packed into a column and washed with 1×PBS until O.D.₂₈₀<0.05. Residual solution was drained. Antibodies were eluted with elution buffer and collected into tubes containing neutralizing buffer. Eluted fractions were dialyzed against 1×PBS overnight at 4° C. with at least twice buffer changes. IgG concentration was measured at 280 nm by nanodrop. The antibody purity was examined by either ELISA, SDS-PAGE or SSC.

Example 11 Antibody Binding Affinity Study by Biacore

Antibody affinity measurement was performed on a Biacore T100 or T200 processing unit. Anti-human Fc antibody or streptavidin was immobilized on a CM5 chip. hATβH or biotinylated hmAb antibodies were injected and captured on the chip. ATβ or ATα at different concentration with/without heparin were injected. Only AT and ATH bound to the antibodies generate binding constants. The binding results were reported as Equilibrium Dissociation Constants (KD) in nanoMoles. When AT/heparin complex was analyzed, heparin at 1 uM is included in the running buffer.

Example 12 Heparinized Rabbit Bleeding Model

Experimental design of the heparinized rabbit bleeding model is outlined in FIG. 13. Following preparation of rabbit jugular veins (right vein: venous stasis; left vein: cannulation), low molecular weight heparin (LMWH) is administered to the rabbit (1800 U/kg) IV in PBS vehicle at time 0. After 10 minutes, the test article is administered. Experimental groups include Vehicle, PBS; Positive control, Protamine sulfate, (28 mg/kg IV); Negative control, M14 IgG2; treatment: 30 mg/kg; TPP2803, 3 mg/kg; TPP2803, 30 mg/kg. Five minutes after administration of test article, an ear puncture (3-5 mm) is performed and thrombus formation in situ (stasis) is monitored over a 30 min period. Blood from the incision is removed every 15 seconds with a filter paper until the bleeding stops.

The foregoing disclosure and examples are not intended to narrow the scope of the claims in any way. It should be understood that various modifications and changes can be made, and equivalents can be substituted, to the foregoing embodiments and teachings without departing from the true spirit and scope of the claims appended hereto. The specification and examples are, accordingly, to be regarded in an illustrative sense rather than in a restrictive sense. Furthermore, the disclosure of all articles, books, patent applications, patents, and other material referred to herein are incorporated herein by reference in their entireties. 

We claim:
 1. A monoclonal antibody capable of binding AtβH, wherein the heavy chain of said antibody comprises: a HCDR1 comprising SEQ ID NO: 40, a HCDR2 comprising SEQ ID NO: 45, and a HCDR3 comprising SEQ ID NO: 50; and wherein the light chain of said antibody comprises: a LCDR1 comprising SEQ ID NO: 21, a LCRD2 comprising SEQ ID NO: 26, and a LCDR3 comprising SEQ ID NO:
 31. 